Cyvern - B:NG error

[DejahThoris]

Well, my Cyvern was working fine a few weeks ago, then stopped booting. Finally got back to messing with it today. I've ensured the voltages are right, and cleaned both the cart, and motherboard connectors.

Not sure what SuperNova boards check on startup, but my A is OK and my B is NG.

It flickers oddly and will go through the only use in Japan, then the SuperNova splash, and restart telling me that A is OK and B is NG. Over and over.

I took a wild guess that A or B may be the two socketed program roms and replaced them with newly burned ones to no avail.

Anyone know what A or B are?