I suspect a partial/resistive short from one of the power rails to ground.
1. Can you provide photos of the bottom of the main board and the bottom of the power supply boards?
2. If you remove power, what resistance to ground do you have in the following locations on the 3v3 board:
? ?a. The rightmost pin of the board connector?
? ?b. The side of D103 closest to IC101 (away from the connector)
3. Do any of these resistances change if you remove the 5V board?
4. Replacing the 5V board, what is the resistance to ground on the?left side of D108 (towards the audio board)
Jonathan KN6LFB
