Genie GS-2646 showing low voltage on charged battery

I just bought a Genie GS-2646. The previous owner said it was good to go and no issues. Looked fine put it through it's paces. Trucked it to my location and it had just enough power to roll down the ramp 10 feet. Now its saying low voltage.

One battery was bad so I swapped that out. I'm getting 25.8v right now which isn't full but I assume low is triggered something like 23v and 25.8 should be great.

The seller is no help saying it was great. They'll take it back which I'd prefer not to...

Genie GS-2646 showing low voltage on charged battery