You could send in the Sansa E280 to here: http://www.pdasmart.com/pda-battery-center/battery_SANDISK_SanDisk-Sansa-e280_battery_center.htm
They will replace your battery for you.
You could also purchase the battery here: http://www.amazon.com/Sandisk-Sansa-Battery-E200-E250/dp/B003E4WL6K
and install it yourself.How do I replace the battery on the Sansa e200 player?
1. Remove the back on the e200 by removing the 4 screws.
2. Lift off the back by using a finger nail or a small flat head screw driver. It will not take a lot of force to remove. NOTE: When replacing the e200 battery be sure that the contacts on the battery line up with the contacts on the player.
3. The battery has three gold contacts on one end of the battery, which is near the words SanDisk Sansa. Be sure these contacts match up with the three gold contacts on the back of the player.
4. Lightly push the lined up battery up against the contacts of the player until the bottom end of the battery can be pushed into place.
5. Replace the lid to the back of the player and then plug the player into the computer using the Sansa cable.
6. Once the player has connected to the computer and is ready to be used or says "Connected", unplug the device. NOTE: If the device goes directly to a black screen after unplugging it, then the battery has been replaced incorrectly. Take the back off the player once again and flip the battery around and the e200 device should work properly.
I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514