Maybe this is helpful. I am not sure which V it is from, but I would be surprised if they changed batteries. It is 2"x1 3/4"x7/8". I have reached out to the manufacturer to see if there is a low-quantity supplier. Of course the batteries are replaceable and disassembly is relatively easy. If I find a supplier, I will post here.
Follow-up. I also found this:
Battery pack
Dongguan Golden CEL Battery Co., Ltd.
104049
7.4V, 2600mAh, 19.24Wh
IEC 62133-2:2017
INTERTEK
Certif. No.: SG ITS-21483
Report No.: 200701045SZN-001
Alternate
Guangdong Pow-Tech New Power Co., Ltd.
PT124147-2S
7.4V, 2600mAh, 19.24Wh
IEC 62133-2:2017
SGS
Certif. No.: FI-45901
Report No.: SZES200700426801
I found that information here: https://m.media-amazon.com/images/I/B1wRGOxxO7L.pdf
Inside it has two PT124147 3.7V packs connected to a circuit board with 4 wires. Red (+) -Black (-) -Yellow (T-) -Yellow (Can’t read yet).