I recently got an SE/30 that booted up to a grey screen with a mouse pointer and did nothing else. The screen was bright and clear though. I took it apart, cleaned the logic board and let it dry completely and then recapped it - there's some minor corrosion from leaking capacitors, but the board is clean and it didn't look like any traces or critical ICs were damaged.
After that, it played the startup chime got as far as the disk with a question mark. Success! So, I turned it off and reconnected the floppy drive to test booting it up, and now it turns on, I hear the startup chime, the fan spins, and you can hear the floppy drive spinning and reading, but the display never turns on. After reading the dead mac scrolls and other troubleshooting docs, I thought it might be R22 on the analog board, but that resistor looks fine both visually and with a multimeter. In fact the analog board looks pretty good overall, no leaking or bulging capacitors, and it was working fine just a few days ago!
Hopefully someone has seen this before and has some advice. Thanks in advance!