Ensure both sides of charging cable is inserted all the way in, if the device is still not working, the charging cable is most likely defective. If problems persist, the battery could possible require replacement.
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If the device will power on, terminate all running applications and launch the device into airplane mode. This will allow for 100% of power to go towards basic function. If the device continues to burn through battery power at a high rate, the battery may require replacement. If the device will not power on, check to make sure battery has no warped edges or bulging.
Ensure both sides of charging cable is inserted all the way in, if the device is still not working, the charging cable is most likely defective. If problems persist, the battery could possible require replacement.