Battery status displaying incorrectly

Hey IFixit guys,

I've had these headphones since ~2015 or so and in the last year or two I've been experiencing a few issues.

• Battery status fluctuates massively while not in use / after charging.

I'll have taken the headphones off the charger and turned them on to get "Battery at 100%" from the audio readout only to then turn them on again a couple of hours later and get "Battery at 20%" or less.

• Wireless connection to my devices drops randomly after startup.

usually, this occurs at the same time the device believes its battery is at or below 10% and I suspect this is tied to the same issue as above

Does anyone have any recommendations for potential repairs? i already suspect a battery replacement may be helpful, but your recommendations or diagnostic expertise is appreciated