Hey Joseph,
Seems that I have a very similar problem as yours.
Unit does not show any signs of life.
I replaced 2 caps on power pcb that were slightly expanded. Still no life.
When I measure volts on batery terminals on a speaker side, I get 18V. However when the battery is connected, the most I get is 8V.
11V battery can’t get charged with 8V. And batt is dead completely. Nothing on any terminal.
Have you figured it out if unit can be operated on AC power without a battery?
Thx