Is it under a year old?
Then you take them up on the warranty. The details are too slim here. But I've seen this on too many Android things. It's not just this make/model device. Sadly the only time we had this in the shop it was cured by a new battery. The owner didn't believe it. Took them a few months to believe and believe me, it may not be that but given how much the battery plays into the device, I've learned to carry a spare.