Mega ST2 Bombs when powered on

I have an old ST2 that bombs out when powered on. Most of the time its 3 bombs, sometimes 2, then sometimes looks like the bombs never end.. Ive reseated everything, from TOS to video shifter, every chip that was removable was taken out.. Removed the floppy, had no KB attached and still have the same outcome. Any suggestions on where to look next?

I guess I could try swapping chips with my ST4, but only as a last resort.

Triads