I bought my player around 10 years ago. Used it several times per week for a first year or two and then put it in cabinet and forgot about it.
Recently wanted to use it again but having issues with battery gauge. After fully charging player battery gauge drops to 1/4 as soon as I disconnect charging cable. A couple of days earlier it lasted about 40 minutes, despite sporadically showing zero charge. Today it doesn’t hold charge. Here’s a video: https://streamable.com/6oq2ho
It has stock firmware. I wonder if resetting to factory settings and updating firmware will help. Will doing this reset battery stats and recalibrate it? Instructions mention to have battery at least 50% of its charge though. If it is connected to PC/Laptop, why does having battery at 50% matter?