when clip is off, battery still lose power + device some times doesn't turn on

hello, I have bought Sansa clip 2gb couple of months ago, and lately I am experiencing battery power lose 

every time after I turn off my device.

1 week ago I went to school (night before I charged my device) and at break time I listened to music, when it ended I turned it off and on the other day when I turned it on there was no battery power and the deviced shutted down. 

this happened in the holiday although. 

But, not only that. Sometimes after I turned the device off (on 80% battery) after few minutes if I tried to turn it on it didn’t do anything 

only at the evening it turned on again! (and again battery lost power).

I was hopping you have some answers for this and maybe a way to fix it.

thx.

You may want to try re-setting the player (on switch in the uppermost position for 10-15 seconds) and/or re-applying the firmware–something may have become corrupted.  Otherwise, the player likely is defective–time to call SanDisk customer service for a defective product warranty replacement.  Sorry!