Hi and
to the forum.
Unless you can find a local GM dealer who is able to supply just the battery, you will probably have to order a replacement battery direct from China.
A quick
Google search returned several results of potential suppliers of this battery, but you will have to enquire about the price and availability.
AliExpress shows a price of $368.42 but unfortunately, the item is "
no longer available!"
If the plastic casing can be dismantled easily
(without being damaged) it might be possible to have the pack completely rebuilt with suitable new cells fitted if you can find someone locally
(with the necessary skills and a suitable spot welder) who would be prepared to tackle the job.
I have not seen what's inside one of those packs, but I'm guessing it will be comprised of 30 x 2200mAh 18650 LiMn cylindrical cells in a 10S3P configuration giving a total capacity of ~6.6Ah which has simply been rounded up to 7Ah for easier advertising.
Alan