Boot Loop - Constant Restart

I have a Sidekick 4G that I'm working on and the device will not fully boot. If it does, after a very brief period of use - it restarts itself and get stuck in a boot loop. The Samsung/Sidekick logo appears, flashes off, and then restarts OVER and OVER again. . .

I fully disassembled the device and disconnected ALL hardware - except for the LCD. Even when this was done, the device had the same issue - it's not possible a fault with the LCD would cause this is it?

When I enter the restore mode (Power + Vol +/-), before I have an option to choose a restore or anything else - the phone restarts itself again. . .

When attempting to charge the phone, it continues to loop as well even when the battery charging icon appears. . .

ANY ideas? Any resolutions? Anyone else experience this? *Note - phone has never been rooted, no water damage, all connections secure. I'm LOST with this one. . .