Aftermarket battery for K2? Repair options?

Anybody have a line on a device repair service that will replace the battery on a K2? I know that Karoo does not offer nor recommend repairs.

Backstory: my K2 has worked flawlessly since the fall of 2021. Never had a problem with the battery or charging until last week after a hot 6 hour ride. I could feel heat coming from the inside, not just passive heat from the summer sun. Would not take a charge, and when I'd try to restart it the H start screen would flash for a second or two before shutting down again. I tossed it in the fridge to help cool it down, and it finally took a charge. Got one more ride out of it and then it went total brick. No soft reset, no hard reset, no white recovery screen. Won't turn on at all with power or external battery connected.

The unit is way out of warranty, and I'm pretty crafty so I thought I might poke around to see if I could get to the battery. I took the two external body pieces off - those accessible with the small torx screws - and that's it - I couldn't see any way to access the battery at all (not like an iphone or my old Garmin 810).

Any ideas or recommendations would be appreciated.