BUILT-IN BATTERY!!

I have a Lenovo Yoga 710 15IKB. It is 7 mos old, purchased from Best Buy. Still under warranty, but not extended coverage for accidents & no special BB memberships. I have health issues, work mostly from home, often in an adjustable bed. Have had issues in the past w/other laptops slipping off...

So I woke up today to my htc desire 820G all good and fully charged checked the time, unplugged it and locked the screen. 5 minutes later I tried to unlock and check the time but found my phone turned off so I turned it back on it worked for less than an hour then started to go off whenever I...