The only thing I can think of is to let the player sit for a week or more so that the battery drains completely. It may seem dead but it’s probably just in a frozen state with a dark screen. Kind of like in a coma. Then plug it into a power source and leave it connected for a couple of days and then see if it’ll start up again.
How long have you had the player? If you bought it new, you may be able to get a warranty replacement from Sandisk if you can’t get it to working again.
