How did you “test” the kick out? Closing the leaf switch for the solenoid? Or pushing the kick out button (which would include a message back to the board and then firing the solenoid).

Did the solenoid fire and stay locked on? Fire and then system locked up? Or never fired before system locked up?

The flashing between two sets of numbers mimics attract mode (high score and last game scores).

Possibly locked in attract mode with garbage numbers sent to the displays. Do the numbers change each time you power up again? Or stay the same (like it was two sets of scores)

I don’t know enough about which boards the mpu needs to boot up, but can you disconnect either or both of the switch matrix (signals coming back from playfield ) or driver board (controlling the kick out solenoids), and see if the system boots up again?