I recently swapped out the RAM in my SZ (from 2 x 512K to 2 x 1MB) and it wouldn’t even POST. Lights would come on, but nobody home.
Turns out I didn’t have one of the modules fully seated. After reseating both new modules it works like a champ. It was a little difficult to get one of the modules to fully seat.
Might be worth checking out.
Jef