Had the same problem after recently connecting my 7150 2 cell Revtech battery backward in one of my cars,(the hazards of direct connect bullets). Turned out the battery has what I call a fuse link in it on the circuit board inside at the bottom of the balance lead connection. I dropped a little solder on the trace and all was well.

It was fully charged and I was wondering why it didn't zap my electronics. I run an old style Tekin RS Pro which might be protected as well. Probably won't be as lucky if I make that mistake again since I've now defeated the fuse link. Car worked fine with different battery.

Not sure if all batteries have this but I doubt it. Seems like it would be a good advertising tool. Of course it would still mean a new battery if you didn't want the hassle of opening it and repairing it but still cheaper than most electronics.