found this on moto tools thread
-Why i don't have signal when i convert to GPE?
Well this is a know issue to fix it flash your stock fsg, don't know how? don't worry.. copy your stock fsg and put it in the tool folder, then press shift+right click and select open window promp here and paste the next code one by one:
fastboot erase modemst1
fastboot erase modemst2
fastboot flash fsg fsg.mbn
this is the radio/modem thread