The link the bweN diorD provided you with is the answer. I can help you get your Root back here is where you need to start.
Begin by downloading SamuraiHL's Downgrade.
1) To install this you will need RSD Lite, I have the latest version which is 6.1.5 (there is an MTK Patch, but this is a file that is not needed). If you have RSD Lite version 6.1.4 and up you are fine,
otherwise download RSD Lite 6.1.5 here.
2) With RSD Lite downloaded go ahead and install it to your computer, which I should mention the RSD version I have is for Windows only. In addition you will need the latest version of Device Manager on your computer. With both RSD Lite and Device Manager installed. Go ahead and open RSD Lite.
3) Pick up your XT926 Droid Razr/Maxx HD and go into Settings> Developer options> USB Debugging and make sure that the check box is checked.
4) Go ahead and put your XT926 Droid Razr/Maxx HD into AP Fastboot> Reboot device by holding Power + Volume (-) down, once screen is black or blank> hold Power + Volume (+) up, press the Volume (-) down button to AP Fastboot mode, then press Volume (+) up.
5) Connect the device to USB.
6) Go into RSD Lite make sure device appears and click to open the file, find the SamuriHL_Downgrade-RAZR_HD.html click to open it and go ahead start compressing and install.
7) This will Revert you back to 4.1.2 System version 9.16.6.
8)
Download Motochopper, from my link here, follow instructions as I have displayed in thread.
9)
Optional/But recommended Unlock Bootloader with Motopocalypse (this is the last chance to Unlock Bootloader, as a new Unlock is not being explored.)
10) Next go into Settings> About phone> Update, and download only the OTA.
11) Install RootKeeper OTA on your device,
here is the link if you do not have it.
12) Go into RootKeeper OTA, select First> Temp. un-root (keeps backup) [this will disable Root hiding a restorable copy of Root.]
13} Go ahead and accept the Install of the OTA.
14) After OTA has installed, device has rebooted, go into Settings> About phone make sure that the System version is 9.18.79/9.20.1 and the new Baseband ends in 15P.
15) Go into OTA RootKeeper and select Restore root. Enjoy!