Your next step would be see where you HAVE power. Use your multimeter and see if your batteries are actually providing voltage on the output side of the holder, at the diode, and at the power pin for the RAM at U25. Once you know where the power isn't getting to you'll know better what the next step is.

Alternately you could contact ChrisHibler or Borygard and send the board out to have NVRAM installed and never be concerned with batteries again.

Sounds like your RAM could be bad. I’d try a factory reset. The chip is not socketed so I’d be sending it out for replacement and have them add NVRAM.

Maybe some corrupt data got into the RAM and the Factory Reset cleared it. Glad you got it sorted out.

Alkaline battery leakage is a leading cause of board damage. You can minimize the chance by replacing them with lithium, using a remote battery holder, or removing them completely and using NVRAM.