Saferam failure - board worked one day, not the next

[BenF]

I bought a test/working MPU board off ebay as a backup to my working GM 7200 upright machine.  Since the battery was toast on mine and wanting to test out the new board after it arrived I swapped the mains (24), graphics (14) and all game chips from my working board to this new one.  After a proper ram clear the game worked great.  The following day though I get the following message at boot up:

"Saferam failure, game disabled. Battery voltage is OK.  Main/Backup1/Backup Saferam (all 3): Fail. Running saferam pattern test. Saferam pattern test passed."

I tried several P10 clears to no avail.  I read other posts here regarding this problem and seems like cold/cracked solder joints at the battery are a common problem.  I reflowed those but still getting the same error.  Battery voltage is good.  I've verified jumper pin settings on both boards match up exactly.  The board itself looks good on the backside, no obvious repairs or hacks.

I finally replaced the battery on my original board and moved all the chips from the new/faulty board back to my original board and it works fine.  So I've pretty much narrowed it down to something on the newly arrived board but am not sure where to check next.  I've contacted the seller, who has all positive feedback, for assistance and assuming I'll hear something but wanted to check here just in case.  Either way I'll post the resolution if/when it's found.  

Thoughts/ideas anyone?  

[idesign]

Check the battery jumper next to the battery.  In order to save the battery it's usually removed.  Compare boards if you can't find it.

[a69mopar]

If the battery isn't installed correctly it can cause this problem.  Check the solder joints at the battery.

W