Just got this phone 2 days ago. Today I noticed the battery percentage stop at 88%. It wasn't going up or down despite heavy use and a short bout of car charging. Plugged it in at home, thinking this is weird - an hour later, come back and it's still at 88%. I restart the device, and yep, the percentage had been displaying wrong all day - it now said 62%. Help. Should this go back to the store immediately for a replacement?