The culprits are C12 (1000uf) and C10 (470 uf) which are the filter capacitors for the 3.3 and 5V outputs respectively. The 12 volt can be as high as 50 mV on a good PS. The AC ripple should be about 5 mV on the 3.3 and the 5 volt supplies when loaded. A defective PS will measure 14.5 instead of 12, 6 instead of 5, and 2.9 instead of 3.3. The power supply is responsible for supplying 12, 5, and 3.3 VDC to the D2A board. Make sure the power supply is working properly before spending significant time on the D2A board. I have been able to repair some of these units. I have been repairing these units lately and have experienced some of the same symptoms (LED goes red but doesn't transition to green after 30 seconds like it should).
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