I have had the same prob with my Thunderbolt since update.  spoke to verizon numerous times and replaced phone 3 tims but problem remains.  phone doesnt turn off when charging, but randomly when not charging and then reboots wit battery power completely drained. i have 3 batteries and it happens with all 3, so not a battery issue.  verizon gave me these responses.  1. factory reset and remove the googlemail acct used to back up your files.  they said there may be corrupt date in your googlemail acct which is going back to phone. also 3rd party apps may be prob.  2. restart phone in safe mode.  you will lose access to certain aspects of phone, but phone may not turn off.  3. remove SD memory card as corrupt data may be stored on memory card. 4. replace SIM card.  well i tried the first 3 options with no success at all!  wasted a lot of time.  now verizon is sending me a new SIM card and i will try that tmrw.  seems to me that verizon is trying to force us all out of the unlimited data plan, as there 1st response to everything is "give up your phone and unlimited data and get a new phone with a crappy limited data plan".  clearly they caused this prob, so how they can act like they dont know how to fix it is ridiculous!!