How to prevent the OTA Jellybean update on Droid RAZR Maxx
(1) If you have root, you can use Titianium Backup, and uninstall "Device Management 3.0" (or some other version).

(2) OR, [also needs root], remove dmclient.apk, dmclient.odex, cmclient.apk, cmclient.odex from /system/app. Back-up these files first, in case you want to update in the future; you will need these.