I have had my Mogul for 11 months. It has worked fine and I have been happy with it. One day I also got the Rainbow color screen. I have never loaded any custom ROMs. What i found is that the isue is with the serial connection on the device. as stated above, when I plugged in the "Y" cable that has the round 1/16" headphone jack, the device would boot up fine.
It will
not boot with the
dual USB "Y" cable. Not sure why? (I hate the strange USB connection and the fact that I cannot get a 3.5mm headphone connection
) Anyway. I also had issues with the active sync function. the USB cable was fine as the phone showed charge when connected to the USB port. I swapped to the Dual USB "Y" cord and Now when I plugged in the junk USB headphone that came with the phone into the USB "Y" cord Active Sync worked. Not sure Why but I need it to work until I can get a replacement. I may see if there is a loose connection on the USB connector on the device. If you care for the device, the only part that gets wear is the connector. (I have a Invis-a-shield screen protector on it so the screen is still perfect!)
I Hope this helps someone.