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Root Please help, M820 Prevail bricked after NV item modified

P

pervlex

Lurker
Hello dear members, I bricked my Samsung M820 Prevail, it now in bootloop, just show SAMSUNG at start up then reboots, the brick occurs when I modified a NV item, well the facts are:

I can put it in download mode then use Samsung Odin to flash all (Boot, PDA, Phone) without problems but again after reboot enters in bootloop

The recovery mode (volume up + power) don't work the phone restarts before recovery mode.

I'm sure that can revert brick if know how to communicate with the phone in download mode to access NV items (EFS partition), but unfortunately CDMA Workshop or QPST can't communicate with the phone in download mode...

Exist a program that can communicate with the phone using Odin protocol to access partitions (EFS) ? maybe a way to backup EFS with odin then modify it and flash it back to the phone?

I know exactly what NV item caused the problem (NV item 1878), I only need to change it, but my phone stuck in download mode... any ideas greatly appreciated !

Maybe I can flash with odin a modified bootloader that enable DM ? or maybe a bootloader that redirect the boot to the SD card to enable DM ? ... ok, ok, it's difficult, but who knows...

Can someone share a prevail backup of EFS (efs.rfs or CDMA.rfs) to flash it to the phone with odin...

I don't know what to do ! ... let me know.

Thank you.
 
Don't give up if anyone can help you someone here can. I am not sure of the file structure of the prevail yet so I do not know how much help I can be but I will try a little later today to get the files you need. Unfortunately I would not know what part of odin to tell you to flash it to.
 
It might be time to call Samsung and try to claim warranty. As far as I know there is no way to edit the efs partition from the Odin/downloading screen.
 
Well at least we have an answer now. Not quite the answer I was hoping for either but now I know to definitely stay away from that area of phone when playing with settings.
 
spagman72 said:
Try flashing a 4 part stock rom... The earliest stock rom you can find for your phone.
Click to expand...

Odin doesn't touch the nv data. (efs partition) this is where your phone's identity is stored. If Odin changed that we would all have the same phone number and msid ;)
 
The way I understand it, the efs partition has to be rebuilt when it is modified (in all Samsung devices?). I guess there's checks and balances throughout or something. If something is modified while another left untouched then the mismatch triggers a brick. This is just a guess on what I've noticed... an educated guess maybe but definitely not exact science.
 
IMEI is hard coded in the hardware I believe... It can get corrupted... But cannot be changed. Sometimes flashing an older stock rom can restore it, it's worth a try.
 
spagman72 said:
IMEI is hard coded in the hardware I believe... It can get corrupted... But cannot be changed. Sometimes flashing an older stock rom can restore it, it's worth a try.
Click to expand...

This makes no sense to me. First you say its hardcoded and cannot be changed then you say flashing an older stock rom sometimes fixes it. So I guess my question is How does flashing an old stock ROM fix it if in your words it is hardcoded and cannot be changed?

BTW - In general with the tools and the knowledge Hardcoded can still be changed and it is not that difficult.
 
Ok... The IMEI is hard coded. The phone system or any other app... Just shows what that number is. When the IMEI gets corrupted, it doesn't get modified on the hardware, it just gets visually modified as in :"an app or phone system may show it as missing or defaulting to the general IMEI (0049)" it's still in the hardware... Just have to find a way to get the phone to display it.... In many cases flashing an early stock rom (usually the one that came with the phone) Can fix it. To my knowledge the only way to actually change the IMEI is to physically replace the chip where it's stored.
 
I should have used the words "restore or repair" the IMEI which is possible by flashing an older stock rom. I know that for a fact cause I was able to do so on my captivate.
 
spagman72 said:
Ok... The IMEI is hard coded. The phone system or any other app... Just shows what that number is. When the IMEI gets corrupted, it doesn't get modified on the hardware, it just gets visually modified as in :"an app or phone system may show it as missing or defaulting to the general IMEI (0049)" it's still in the hardware... Just have to find a way to get the phone to display it.... In many cases flashing an early stock rom (usually the one that came with the phone) Can fix it. To my knowledge the only way to actually change the IMEI is to physically replace the chip where it's stored.
Click to expand...

That leads me to a few more questions like if it is hard coded then how can people clone the IMEI or in this case MEID from one phone to another? I mean I doubt most of the people that do that take chips from one phone and put it in another and it's doubtful that they own the tool to read and reflash the EEPROM on that particular chipset.

And not all phones are created equal if that were the case there would be no need for porting ROMs because they would just work. Each phone has different hardware leading to different software and in fact if the MEID is hard coded and cannot be changed then the cloning would not work.

That being said any software including software that calls for hard coded information can be changed in one form or another through it is a process called spoofing.
 
Sure... All phones are not equal, back in the day it was much easier to change IMEI. I own a Samsung tool box that repairs IMEI (can also be done with other tools) many of the chips that the IMEI resides in is read only... I'm sure there are ways to spoof etc.. I know many people that are running on the default IMEI number (0049) and are fully functional and have been for a few years. Like I said different phones.... Different hardware... And yes I did hear people switching out the chip to get a new IMEI
 
I don't know anything about hard coding and all that stuff but for me, if I could get odin working I would just try the stock Rom and if that don't work just claim a warranty. I really bricked mine, would not even power on. Sent it to Samsung, they replaced board and sent it back, no cost to me. Took all of about 8 days.
 
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