Random Restarts, No BSOD just black, wont post or boot sometimes

Acer Aspire E5-571G

Googled very much everything.

Already did:

''Tried trying other charger

Reseating the Ram

GPU displays on external monitor

Updated BIOS to latest

Reformatted''

im suspecting the cmos battery is defective everytime the laptop restarts

the time changes from a 12 hour to 24 hour format vice versa.

any suggestions?

havent tried reapplying themal paste

dead mobo? had this acer aspire e5 571g for almost 3 years eveything seems fine

until rare restarts last august 2016 now laptop seems unusable as of the moment.

havent been dropped or any accidents.