Chain,
Take a look around the following components:
U13 (Keyboard Micro) pins 1 & 38, are the solder joints bright? These pins provide the PWR_BAR and KB_RESET signals respectively.
Check R626 and R623 are soldered OK, R626 does nat have a value in the schematics but it should be 1-10K I guess.
Put a volt meter on pin 38 of U13 and press and hold CTRL-AMIGA-AMIGA, does the output go from >2.4V to <0.8V? Try this again after the computer has been on for 20 minutes.
The
A1200 schematics are here
