@russww - Sadly, the micro-controller has failed within this battery.
One of the problems many have faced with COVID and the Ukrainian war is the tight supply of microelectronics.
Even the auto industry has had serious supply and quality issues. Surprisingly, this micro-controller is used in many laptops and there are lots of reports of failures within the industry.
For comparison we had a simulator issue quite a few years ago when the capacitor electrolyte chemistry was messed up with a bunch of capacitor makers [https://en.wikipedia.org/wiki/Capacitor_plague|Capacitor Plague]
So you will need to contact the iFixit Store to get a replacement.