Byteboi won’t turn on

Assembled Byteboi and worked fine. Put aside for a few months. Finally got around to building next project and when Byteboi is turned on nothing. Thought maybe kid left power on and killed battery. Battery has 4.1v. When plugged in I get the white led on for about 10 sec and then goes off. Also won’t turn on when plugged in. Removed sd card same thing.