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Note: Root or CWM recovery is required to backup or restore your NVRAM using this method

Have you ever had a problem with your MTK6582, MTK6595, MTK6577, MTK6589, MTK6589T, MTK6575, MTK6572 NVRAM.

Possibly you're seeing MTK Baseband Unknown in your phone settings > phone info after you flashed a ROM with SP Flash Tool or factory reset.

This is what saved Gizbeat after he bricked his baseband.

Normally it's quite easy to find a backup ROM if your phone is moderately popular, but NVRAM in .tar and .bin are often more difficult to come by.

If you don't have a full 'raw' backup with nvram.bin and userdata_nvram_only.tar, take a few minutes and at least make this NVRAM baseband and folder backup.

What you'll need

ADB Drivers (See MTK General Tools Sub-Forum)
MTK Droid Tools (See MTK General Tools Sub-Forum)
A Rooted Phone


What to do

1. Install ADB Drivers
   
2. Extract MTK Droid Tools
   
3. Run MTK Droid Tools
   
4. With your phone on, connect it to your PC via USB
   
5. Root Shell is required. You need to be booted into ClockworkMod Recovery (CWM) or be fully rooted already. If fully rooted, the square should be yellow. If the square is yellow, then click the root button in bottom right corner. The little box should turn green which means you should then have shell access to backup or restore NVRAM.
   
6. You may see a Super User request pop up during this procedure on your phone's screen. Allow it.
   
7. Click NVRAM/IMEI
   
8. Make sure both '.bin' and '.tar' are checked.
   
9. Click backup
   
10. Save them to a place where you'll be able to find them
    

Restore

To restore NVRAM to your MT6589, MTK6589T, MT6595, MT6582, MT6577, MT6572 phone, follow the same procedure but click 'Restore' and direct it to the backups.

Yes, that is great, but i have an brick my phone.
Can any help me about rom original for s 820, not Lenovo!
S820 MTK6572 Android 4.2 Dual-Core WCDMA Bar Phone w/ 4.7"
thanks W

my backup/restore option is grayed out

Jompha, I've amended #5. You do need to be properly rooted or have CWM to complete this procedure.

(2014-02-05, 18:37)Gizbeat Wrote: [ -> ]Jompha, I've amended #5. You do need to be properly rooted or have CWM to complete this procedure.

Hi
I have problem with my lenovo s750 after update i think i lost nvram, because I have problem to cal.
I have always message
"Invalid IMEI"
I was tried many solution update once again, orginal ROM, update efs but without any effect.
Could you help me ?

Everytime I've tried to flash my phone I click 'download' but nothing happens it just stays on 0%

If you don't have a rooted phone droidtools won't backup nvram. The only way to backup nvram is using the information in the scatter file and use the readback funtion from flashtool to make the backup of your nvram partition
(you have to do this manually, so you need to know what information to use from the scatter file, else forget this post).
This will include all information, binaries and config files, even the ones used for the wifi mac address and a lot of calibration files.
You can later restore it to your phone simply by downloading the file with flashtool, no need for any conversion as it is a raw binary file.

Navram backuped on Kitkat rom are impossible to recover on Jelly bean why ?

Probably because you're doing something wrong. Or its something other than NVRAM causing the problem, or things have changed significantly between the two ROM versions.

Flashing the system partition from kitkat to jellybean doesn't work either, why? Because these are totally different kernels which expect the right data in their predefined positions.
The nvram backup files are image files, that is, raw bit to bit transferred files. When kitkat expects a certain value in nvram to be in location X, the same value in jellybean might be expected in position Y. Even though nvram contains normal text files, it also contains binary files with certain data in predefined locations.