Don’t open the player. First try manually reapplying the latest firmware. Buttons not working might be due to the firmware in the player becoming corrupted. If that doesn’t work, then get it replaced by Sandisk under the warranty.
http://forums.sandisk.com/t5/Sansa-Clip-Sansa-Clip/Sansa-Clip-Firmware-Update-01-02-18/td-p/280756
