"amp only comes on with regular power switch or when in sleep mode when pressing play"
Exactly. By the way I meant to say SW15 earlier, not SW16. The main power switch is SW15, and SW20 is the leaf power switch on the deck for sleep mode. These two switches are the only entry points for power on the node powering the power indicator LED. Somewhere else on that node, power is getting through that shouldn't be, but where?
It's a matter of elimination, maybe start by disconnecting main power switch SW15 completely and see if the LED is still on when you plug in AC. Then, disconnect SW20. They are on wires so it should be easy to try. If the LED is still on then you're getting power to that LED in a way that's going around both power switches.
"Q801c seems to test high on voltage."
Q801 is the voltage regulator and the collector is the input. The output, the emitter, goes all over the place. Try pulling Q801 out and see if that kills the power LED. It would be good to rule out anything bleeding through the emitter to the collector. There's a lot of stuff connected to the emitter. If you follow the wire on Q801-E, it zigzags down and to the left past the lamps PL1 and PL2, and splits left and right. To the right it goes to the other page to the VU LEDs and deck preamp. To the left, it goes to the tone controls, and to radio switch SW7A, which gives power to the tuner, its LEDs, and the rec/erase heads on the other page through marker J.
As I can see in your screen shot you've traced the yellow wires for the LED in and out of the power indicator drive PCB and over to the power supply board plug where it hops from pin 7 to pin 6 to join main power switch SW15. Then, it goes north on an orange wire to the power amp board. if you keep tracing the node on the amp board, it first goes right away into Q801-C, R802, and an orange wire over to C561 and pin 1 of the amp, but also runs north on a trace and through a jumper wire to cable JM1, which goes to the other page into the rec/play amp PCB on J107/P107 pin 5. It runs on a trace over to J106/P106 pin 3, where it goes out on an orange wire to leaf switch SW20.
Anywhere along that path could be where the problem is, so maybe unplug one or more of those those plugs and see if it starts to turn off the LED when plugged into AC but shut off.