Hi,
Sounds as though the battery has failed and needs to be replaced.
I couldn’t find a battery replacement guide for a Sansa Clip but here’s a [https://www.youtube.com/watch?v=ramuFlFGSr8|video] that shows how to replace the battery in a Sansa Clip+ which may help.
Here’s a link to a [https://www.ebay.com/itm/Original-Sandisk-Sansa-Clip-Replacement-Battery-Pack-New-/362947422824|supplier] of the battery that may also help