[Atrix 4G Q&A, Help & Troubleshooting] mattaw2001:
Here is an attempt to provide a definitive answer to what to do if your phone has the Bluetooth/Wifi hardware failure.

Note that some of the links don't seem to work with the xda-developer app or the Atrix built in browser. Please blame motorola, not me :)

Symptoms:

1) If your phone was set to try to use Wifi by default on boot:

Your phone boots into the OS but shortly afterwards freezes and reboots - and again and again.

2) If your phone boots with Wifi turned off:

Your phone boots into the OS and a few seconds after you enable the Wifi in settings or via a widget it shows "Error" and sometimes the phone reboots shortly afterwards. Bluetooth simply fails to work.

If you have warranty return it for a repair. If not the best you can get is to disable the Wifi and Bluetooth so the phone doesn't reboot and can be used with mobile data. Instructions for both are below:

Be sure it is the Bluetooth / Wifi hardware failure:

1) Are you running a custom ROM? - if yes go to 1.1, if no goto 2.

1.1) Reboot into recovery and make a backup.

1.2) Remove your SD card.

1.3) Reflash using RSD to stock - remember to get the right one for the right country!

Get RSD and drivers here:

http://xdaforums.com/showthread.php?t=1136261

Search for your stock firmware using google

Use RSD to install the stock firmware file which will replace the bootloader, recovery and radio - takes about 20 minutes.

Goto 2.

2) Reboot into Stock Android Recovery and reset to factory defaults

https://motorola-global-portal.custhelp.com/app/answers/detail/a_id/60620

2.1) Reboot to Android and try enabling wifi from settings - if it reports "Error" after a few seconds and your phone may reboot shortly afterwards it is the hardware fault. Proceed to 3.

3) Check your remaining warranty here:

https://motorola-global-portal.custhelp.com/app/answers/prod_answer_detail/a_id/82507/p/30,6720,7898

Bottom left - enter your IMEI.

Warranty left goto 3.1 else goto 4.

3.1) Return to Motorola for repair - be sure you flashed back to stock first using instructions in 1.3

4) Unpalatable options are all that is left. Either pay or do without Wi-Fi and Bluetooth. Have money and the desire to fix your Atrix ($110 in the USA)? Goto 4.1 else 5

4.1) Consider paying Motorola to repair the phone anyway. Schedule a repair here https://motorola-global-portal.custhelp.com/app/answers/prod_answer_detail/a_id/82507/p/30,6720,7898

5) This is a complex process. Google is your friend. Unlock your phone using the instructions below. Note you have no warranty to lose (see 3)!

http://xdaforums.com/showthread.php?t=1136261

5.1) Install romracers CWM custom recovery using moto-fastboot (or Android fastboot):

http://xdaforums.com/showthread.php?t=1204500

5.2) Did you take a backup earlier? If yes go to 5.3. If no goto 6.

5.3) Reboot into CWM recovery and restore your backup. Note if you are stuck in a bootloop this will be ok in a bit. Goto 7.

6) Install your favourite ROM using CWM recovery from a SDCARD or by moto-fastboot. Goto 7.

7) Reboot into CWM recovery

7.1) Plug your phone into your PC (you might have to wait for the driver to enumerate the phone first)

7.2) Find or install adb on your computer (hint - it comes with the Android SDK and platform tools from earlier):

adb shell

mount /system

cd /system/lib/modules

mv dhd.ko dhd.ko2

reboot

8) When you install a new ROM or kernel goto 7. Every time.

This little setup moves the driver linux needs to try to talk to the wifi/bluetooth chip which has failed so it can't find it. If it can't find it then it doesn't try to talk to the dead Broadcom Bluetooth Wifi chip that prevents the reboot cycle happening.

The fix was pioneered by:

mvniekerk

http://xdaforums.com/member.php?u=2353874

So go thank him!

In the hopes this helps,

Matthew