Fastlane Z3 SCSI won't boot anymore

[MagerValp]

I've been using a Fastlane Z3 for SCSI in my A4000 for the past few years, and it gave up the ghost the other day. I was watching demos from Revision when one froze and I had to power cycle the machine, but after that it won't boot anymore. The symptoms with a SCSI device connected to the internal 50-pin connector are:

• The CyberStorm Mk2 shows the rainbow flash
• After that a black screen
• No early startup menu if I hold down the mouse buttons
• I tried another SCSI drive and got the same problem.
• If I disconnect the SCSI drive the machine boots successfully from internal IDE or floppy.
• With no SCSI drive connected 8512-10/11 shows up as working under expansion boards in the early startup menu.

I replaced the three electrolytic caps because why not, but that predictably didn't change anything. Physical inspection of the board reveals nothing of note.

If anyone has any suggestions on what to try next, please let me know. Otherwise can anyone recommend a good repair service?