Note: This is ONLY for XT910 variants. Flash at your own risk. If you brick the phone, it is a risk you have to bear. We will not be held responsible. DO SO AT YOUR OWN RISK.
Method by: almstag (XDA-Developers Forum)
This is what happened to me.. i purchased a brand new Motorola Razr XT910.. and soon after that, before i even rooted the device.. i did the OTA update.. BIG MISTAKE.. turns out the new firmware 65.1.21.xt910 cannot be rooted.
So the only way, at least as I am writing this guide, is to downgrade, root, protect root, and revert back to 65.1.21.xt910.
So here is a guide from almstag, of XDA-Developers forum, which is the guy who’s post helped me root my phone.
First, you will need some files.. download these in advance.
3. Fastboot File: Download SPDREM_U_01.6.5.1-73_SPU-11-PASS-10_SIGNEuropeAustraliaEMEA_USASPDRRTGB_HWp2b_Servi ce1FF_fastboot.xml.zip
4. ROM for Razr Asia Recovery
5. Root Files (DooMLoRD_v4_ROOT-zergRush-busybox-su.zip)
6. Razr Bootstrap Recovery
Lets Start with Downgrading via Fast Boot
OK.. currently there is no Fastboot for 65.1.21.XT910.PSHAsiaRetail.en.03, so we are going to do, is to flash Europe’s Fastboot file 651.73.23.xt910.retail.en.eu to your phone.
Step 1: Flash the 651.73.23.xt910.retail.en.eu to Your Phone
1.1 Boot your phone into AP Fast Boot Mode
Switch off your phone, then hold to the power key + Volume Down + Volume Up
You should get something like this
1.2 Connect your phone to your PC Via USB cable
1.3 Flash the firmware into your phone
Step 2: Root your phone..
2.1 Extract the Root files you downloaded earlier (DoomLord)
2.2 Enable debugging mode on your phone
Go to Settings->Applications->Development->[Tick USB debugging]
2.3 Connect your phone to PCl
2.4 Set USB connection to “Charge Only”
2.5 Run the “Runme.bat” from Doomlord’s file
2.6 Thats it.. your phone is now rooted.
Step 3: Bootstrap Recovery
3.1 Install Razr Bootstrapper (APK) to your phone.
You will need to copy this APK file to your phone’s SD card
3.2 Copy the Razr Asia Recovery.zip to your phone’s SD card
3.3 Run Razr Bootstrapper
3.4 Select “Bootstrap Recovery”
Superuser will prompt for permissions
3.5 Select “Reboot Recovery”
3.5.1 The phone will reboot into Clockworkmod Recovery
3.5.2 Select “Install zip from SD Card”
3.5.3 Flash the software
If you are unable to complete this step, please skip to the last part.. because i encounter “installation aborted” error
Step 4: Preserve your Root
4.1 Install from market Voodoo OTA Rootkeeper
4.2 Backup the Root
4.4 Install the 65.1.21.XT910 update (OTA)
4.5 Use Voodoo OTA Rootkeeper to restore root
Ok.. now for the difficult part. What if you encounter problem at step 3. I encountered installation aborted error message. No matter how many times i try, i still get that error message.
Thanks to almstag from XDA-Developers forum, he taught me what to do.
1. Download this stock ROM
2. Make a folder on your ext-sd and name it “clockworkmod”
3. Go to clockworkmod, and make a new folder inside it, named “backup”
4. Extract the downloaded 6.5.1_73-spd-ird-12 into the backup folder (ext-sd\clockworkmod\backup)
5. Run Razr Bootstrap on your phone and go to recovery
6. Scroll down into “backup & restore”
7. Restore 2011-12-188.8.131.52
8. After complete, wipe cache, and then reboot.
DONE! you can now proceed with step 4.