Is my TI-58C hosed?

[Dave Britten]

I've got a 58C that I snagged from ebay a few years back, and finally got around to restoring it to operation. Mainly that just required building a battery pack: a 3x AAA receptacle soldered to the two contact pads on the board, with a trio of NiMH cells inserted (didn't want to spend a lot on a more sophisticated battery until I could be sure it works). I don't have the A/C adapter, so I'm not worried about the chemistry being different.

It worked great pretty much immediately when I did this last week, and I messed around writing a couple small programs, and trying stuff in the Master Library module. All the included diagnostics looked good, and I could get a couple hours useful life from the AAA NiMHs.

Now, a couple days after using it last, I suddenly can't store any program steps or register values. Everything reads back as 0. Also, the Master Library diagnostic routine (2nd Pgm 01 SBR =) returns a flashing 1. I checked the batteries, and tried a spare set, so it isn't low on power, I don't think. Is the memory chip or the constant memory circuit fried?