Naomi 2 is in a Naomi Universal cab, original PSU. Original BIOS 23608, swapped with 23608-A. GD games Virtua athletics, works with 23608, GGXX Slash, worked with 23608-A. Cartridge Virtua Striker 3, works with 23608. I have 2 GD-Drives, I get the same result with both.
I have tried the following to narrow down the possible fault, all results as expected:
Run cartridge with jap BIOS (Error 21).
No Dimm board (Error 01).
With Dimm but not connected to GD-Drive (Error 25)
With Dimm, connected to GD-Drive, but GD-Drive not connected to power (Error 25)
With Dimm but cover GD-Drive cover open (Error 23)
With Dimm, GD-Drive cover closed, no game (Error 24)
The did the following tests in the test menu:
Tested RAM without cartride, all good.
Tested ROM board, all good.
Tested Dimm board without game (prog. ver. 1.02, all good except Dimm status = bad and GD Drive bad).
Tested Dimm board with game, I get a Dimm board time out message and "Unknown game" is displayed in test menu