Here is the update. Turns out the power supply DC-DC converter does not power the button leds. My track tracing was in error.
The DC-DC has a 12v input, and puts out -32v, -38v, +5v, +3v. The +5v does go into the board to power one of the led control chips.
The power for the leds comes from the main board. My tests show it isn't working, no +5v on the input pin from the main board.
However, there were three other switched +5v outputs that switch on when the lights are on, they go to the control chips to turn on
the leds. So instead of taking the radio all apart to get to the main board, I just made all the leds on when the lights are on,
instead of having the processor customize them by mode. The control chips just connect the negative to ground, so I just soldered
those leads right to ground. The second chip I removed and soldered the leds traces to ground. There are different groups of leds,
so that was a pain to determine which chip pin do which leds. Then I jumped over one of the +5 inputs to the led power,
and now it works! So turn on the lights and all the buttons (well most all, the channel buttons do) light up.
So a lot of work, but I am happy camper now.