Sir Wawaslipshod . . . . . .
Just from the aspects of what we CAN see there.
How about taking DC voltmeter in hand and set to the greater than 12VDC dc range and black negative lead to the metal shield box at top center and then red probe test and log down the voltages being at the 3 lead (plus a top tab) semiconductor being just to the right side of the large black can radial electrolytic . That will be the top, middle and bottom three leads on it.
Then drop down to the bottom left to the two heatsinled devices U7----U8 and log the voltages on the three leads of each.
If you are even getting voltages, we at least know that there is some action from the earlier power supply circuitry coming into the power input connector at the top left board corner and up to these devices.
I noticed a small brownish spot on the right side of the picture in front of three plugins (white). Just cheeeeeeeeeep brown glue., left opened all day to age and progressively darken weekly.
Also the wires going into the middle plug look suspicious to me.
That looks like it should be 4 interconnecting wires to speakers form a possible power audio amplifier as the 10 lead Single Inline Package IC mounted to the heat sink
73's de Edd