Assuming your son has not tried to "upgrade" the player then it looks like a component failure in the charging circuit.
If you would like to try to repair and your son can solder and do some electronics there is a schematic for this type of player in the downloads.
Since you have only had the player 2 weeks, it would be best returning to the seller for a refund or replacement.
btw don't blame your son, many of these players are very poorly made, a lot of people are having problems with them, .
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