Have you tried using another charger? I have had this with Android tablets. If they have a really really flat battery it is like they have so little power they won't even start to recharge when their normal power cable is plugged in. I have found a short charge from a lower power charger seems to give them just enough power that they will then recharge properly from their usual power cable. Chromebooks and tablets usually need chargers which are at the top end of the Amp range (2A or 3A) but a short charge from a 1.2A mobile phone charger can do the trick.
LP
May 2021