IIgs Motherboard Issues

["Polymorph" <polymorph69@hotmail.com>]

I have a few issues with a IIgs ROM 01 motherboard that I recently
picked up from eBay that have me stumped.

Firstly, the IIgs clock battery arrived dead (not unusual), so I
replaced it with a 1/2 AA lithium battery (soldered it on). However,
the clock still refuses to work when the AC is turned on, but it does
seem to keep time when the AC is off? If leave the computer turned off
for a day or two, the clock and all the settings are forgotten. I have
put my multimeter onto the board and it seems to be getting the correct
voltages from the new battery, so I'm stumped??

The second problem I'm getting is a failure in the self test -
0B050000. I checked the A2 FAQ's and unfortunately this is the only
error code "not documented". From the FAQ, I have determined the
failure occurs in the "Interrupts Test (Mega II and Video Graphics
Controller)" test, but because this error is undocumented I can't find
out what it means.

Does anyone know if the two problems are related in any way? Is it
likely to be repairable, or am I up for a new MB?

Thanks
-p