Restore Your Motorola Droid RAZR from Bootloop Using Fastboot Files

If you own one of this famous device, and ever you get in a situation where your device stucks while booting, don’t panic. There is a way to recover your device by flashing fastboot files. You should consider your device as not booting if: it’s stuck at Motorola logo, or if the boot animation is playing longer than expected, or if your device is vibrating constantly after some intervals. Fastboot files are the stock firmwares leaked from Motorola which will make your device restore back to the factory condition.
Note that Motorola Droid RAZR has a permanent locked bootloader and due to this, it cannot be downgraded to a lower version of Android. Don’t try doing it or you might risk bricking your device.
If you have upgraded your device from Gingerbread to ICS, then you must flash ICS fastboot files or if you have recently upgraded your device to Jellybean via OTA then you must flash Jellybean fastboot files.
Disclaimer:

This is a risky operation. This procedure has been verified to work, and you will be flashing your complete internal memory, including the internal storage. Your SD card will not be touched though. If you fail to follow any of the instructions properly, you could permanently brick your device. Reserve this as a last option. We don’t take any responsibility if anything happens to your device.
Prerequisites

• You will be needing a Windows PC.
• Motorola Drivers. Download them here: Motorola Drivers
• You must have setup ADB properly on your PC. This is an important step.
• See our detailed guide to setup ADB properly: Link
  
• A software called RSD Lite which is used to flash multiple Motorola devices with multiple flashing methods. Version 5.6 or above is recommended: Download RSD Lite 6.1.4 here
• Download fastboot files for your Droid RAZR from following XDA posts. Carefully choose your version and your device(XT910/912): Source 1 Source 2 Source 3(Jellybean)
• A fully charged Droid RAZR (or at least 80% of battery)

Boot your device into AP Fastboot mode

• Power down your Motorola Droid RAZR
• Press Volume- and Volume+ keys and press Power key, hold them until you see a list.
• Press Volume- to scroll down to AP Fastboot and press Volume+ to select the option
  (You can use only Volume- to scroll, pressing Volume+ will select the current highlighted option)

Restore your Motorola Droid RAZR

• While in AP Fastboot mode, your device should say: Battery OK, if it does, plug in the USB cable to your device and into your PC’s back slots (neglect if on a laptop).
• After connecting, you should see driver’s being installed for your device. Make sure your PC detects it as an ADB interface device (if it doesn’t, you might need to recheck your ADB setup). Don’t proceed unless you have passed this step.
• Extract the downloaded fastboot firmware into some folder on your Desktop.
• You will get an XML file, now run RSD Lite and browse to the extracted folder on Desktop and choose the XML file.
• Check if your device is shown connected in RSD Lite.
• Finally click on start. This is a very sensitive task. Wait and stay tight until the process finishes. Don’t dare to touch your device until it finishes.

Troubleshooting

Your device will reboot several times during the process. If the process finishes and your device does not boot, you might need to clear the cache, to do that, head to recovery:

• Power down your device. You can also force restart your device by pressing and holding down both the Volume keys and the Power key for about 10 seconds.
• Press Volume- and Volume+ and press Power key and keep pressed, from the list scroll down to Recovery with Volume- key and select with Volume+ key.
• When the Android logo is shown, press both the volume keys and wipe the cache from the menu shown
• Now try to reboot, if it still fails, you might have to consider flashing again

thanks to the original author!!!!