oh my god, so many questions ok, I'll try to answer em all.
''i have a pc sutie backup of previous firmware. but if i restore it, i only will get the files, no change will be done on firmware.'' - yes, that's so. And in PC Suite there's also said, that before restoring previous version, u first need to format phone.
''what is CDA ?'' - umm, where did u get that filename? its a program, file extension or something else? please tell a bit more about it (or at least link where u got info about it)
''and what's SEUS'' - Sony Ericsson Update Service, its for SE not Nokia.
''do i need to format memory card ?'' - I think no, but PULL IT OUT BEFORE FORMATTING PHONE, or u might damage it... and better pull out also sim card (or put in any unneeded sim card - just to secure ur phone numbers, important sms etc)
'' in that case, i should do it before hard reseting, shouldn't i ? '' -better not format memory card, just take it out. Because I don't think that there is that new firmware installed (and btw where did u install that firmware? i mean in phone memory or memory card?)
''and after hard resetting, the included apps like calender, clock,file manager, adobe pdf, flash lite 3, java, converter, calculator, maps, share online etc softwares that was included to my phone, that i got when i bought it 1st, will they be available after hard reset ?'' - after a bit searching in Google (but u better try to search more about it), I've found, that it doesn't removes included apps and evertyhing (but don't forget to backup also your phone that u have right now (in some case, if ur previous backup is corrupted or anything..)
''is there any problem that i may face after hard reset ?'' - umm, I haven't done that ever, so im not sure... but in such a case, u will have a backup, to restore this firmware (or better old firmware bakcup), and i think, in such case (i think there should't be any problems later) it would be better to have new firmware phone, not not-responding phone
'' or do u know any other methods to restore previous firmware ?'' - I searched for it a long time, and didn't found any reason... BUT, nowhere was mentioned that genial idea about reinstalling phone, so, its worth to try. And maybe, but maybe, might help leaving phone battery-off for several weeks (but it might also not help...) so i don't know any other method...
'' that link.... i don't want to test it. i think it won't be successful.'' - yes, i also thought about it, because I read it... and after that searched some reviews, how successful was it, in most of cases (using that method), there were many problems etc etc etc...
so, I think i replied very well if any more questions or anything, just write!
hey, nice idea about reinstalling phone! haven't thought about it! but, how gonna you do that? mmm... maybe if you have Nokia PC suite backup with that previous firmware, then if you format phone and everything else (restore backup using nokia PC suite) you should get brand new installation
here i found something useful for u (how to format phone):
--------------------------------------------------------------------------------- -- Q: How do I format my phone? A: - Normal Reset (*#7780#) : Restores ini files from ROM but preserves user data (photos, 3rd party apps etc) - Deep Reset (*#7370#) : This reformats completely the C: drive. All applications and files stored on this drive will be lost and clean default files will be rewritten. (i think this should work for u Swagata)
In both case, the phone will ask you a confirmation and you will have to enter a security code (12345 by default).
Files and applications stored on E: drive are not be affected by these sequences, also SIM card arent affected!
For Symbian OS 7 (6260/6600/6620/6670/7610) there is a third method: Turn phone off, press and hold the green (talk) key on the left + number 3 on the keypad + the * key and then turn the phone back on.
The phone will start the formatting process WITHOUT NOTIFICATION <<<<< Files and applications stored on E: drive are not be affected by this. (in that case, you should copy all files on your PC from memory card and then manually (using PC) format memory card too, I guess) --------------------------------------------------------------------------------- -----------------
but for security reasons (if something messes up or anything) make another backup of phone using NokiaPC suite!
and I found another: ''Well you can try two different approaches: 1. Perform a MAJOR reset by formating the internal disk. This will totally whipe your phone to factory defaults. That is, it will also remove all installed languages except default (usually english, depending on which CDA you have or if it's branded), all themes except the default theme, some ringtones (rare cases) etc.. (nothing critical and it will not do anything with the memory card storage). You may have to use SEUS afterwards to re-flash your phone to get it as it was "out-of-the-box" but it will most definetly work fine after the format.
To open the hidden system menu do the following by "typing": * jogdial UP * jogdial DOWN jogdial DOWN * jogdial DOWN * => Select option "Format internal disk"
i think reformatting should remove your firmware update... because it removes all installed files and everything (phone book, sms etc - so make a backup or something)
please report how u did, if it will not work, gonna search more information about how to restore firmware or reinstall os
edit: oh, and also, you can find previous firmware installation and install it over current firmware?
thanks for coming back to my site Swagata oh, yes, if u have latest firmware installed, then its sad... because there isnt any method how to hack new firmware, cause there Nokia added some kind of security of hacking... (that really sucks) umm, about this site (http://handphone-solution.blogspot.com/2008/08/how-to-hack-for-new-firmware-with-anti.html), yes, FCA has found something, thare are posted some files, maybe they will help u, to hack new firmware... files: http://redpepper007.ucoz.com/load/0-0-0-10-20 say how it will work, and ill try to find a new way, how to hack newest firmware phones.. at the bottom of this site http://www.symbian-freak.com/quides....ion.htm there is a some kinda tutorial for those new files, please reply, if it will work on ur phone (then ill post it in my site too :))
edit: I looked how to downgrade nokia firmware, but found, that its impossible... and u can maybe try program called CapsOnOff... (also meant for hacking) edit: and btw in this site http://symbianhack.site666.info/ under the text, there are several methods of hacking phone (try em also glad 2 help u ask more questions or anything
Swagata Howlader hello in my page and thanks for registering umm, about unhacking im not sure, but it wont be necessary, because hacked phone is much better that unhacked
and that ur problem, emm, i thinnk trat u don't need to make that bin folder, because its already there full of system files! and also copy to "C:/sys/bin", C not E or any other (because C ir phone memory, but in memory card there is also a folder called bin)!!! probably u havent correctly done these steps or maybe try again:
3. Install again Hello_Carbide_by_FCA00000.sisx
Install HelloCarbide either on your phone or memory card. After it's done, you'll noticed that you have a new application called HelloCarbide (without an icon). DO NOT OPEN IT YET
4. "Applying the proper InstallServer.exe" Now open your file explorer (must enable "show hidden files and folders"), DO NOT EXIT but switch (press and hold the menu button) to your standby mode then open HelloCarbide. You'll notice that it has no welcome screen or what-not, just press Options -> Menu1 -> Yes. If done correctly it will close itself. Now you have all the capabilities on your phone, much as BiNPDA's Security Manager. Now switch back to your file explorer. (also pressing and holding menu button) (You must not open any other application other than your file explorer). Copy the proper InstallServer.exe on "C:/sys/bin" (if there is no "bin" folder, then make one). Exit from the file explorer. Do not do anything else, just RESTART (turn off and then on) your phone. Feel free to uninstall HelloCarbide afterwards.
install hello carbide, but dont open it yet. open ur xplore, then switch to standby mode, open hello carbide, press Options -> Menu1 -> Yes. then switch back to xplore (remember to enable show hidden and show system files), then u will be able to see the correct bin filder (ive noticed, that in my nokia 6120c there are several bin folders, doh :D)
you're welcome catamaran:) and baoji n Swagata im writing answers to u right now, need 2 search a bit
you guys are the first people, who posted comments on my site!!!
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baoji, first of all, u don't need to install that install server file (it will be installed when u restart phone - if u have put it in right place), and about that xplore - maybe try one of these:
hacking can't be harmful for ur mobile, if u do everything as I said in tutorial. Btw, at first time, when I hacked my phone, I also was a bit scared, that somethings gonna change or not work or anything, but guess what - nothing changed after hacking - except that, there weren't those ''expired certificate'' or ''certificate error'' ... errors smile
no, nothing bad cannot happen, if u do as in tutorial!
your mobile will work just as it works right now - hacking just removes those annoying errors, that's all!
don't be afraid smile
so, about that if its possible to hack ur phone - I guess yes smile btw you cannot mess something up or anything smile first time when i hacked my phone (nokia 6120c) I installed wrong InstallServer.exe file to my mobile - but nothing happened smile after restarting my phone just wasn't hacked smile so I tried again with the real InstallServer.exe for my phone, and it worked biggrin please reply, how u did biggrin
everybody feel free to post comments, I'm glad, that I can help u and u visit my site smile
ok, I'll try to answer em all. 
