a little problem with my Nexus 5
i just got my nexus 5
but it has a little problem
i unplugged the charger this morning and started to installing apps
and i just installed Viber , Clash Of Clans , Instagram and airdroid
the phone just worked fine and no problem until 1 hour ago
since then , when i lock the screen ( manually or automatic lock screen ) and then i want to unlock it again , it doesn't work and when i press the power button it has no response
now i locked the phone and watching it restart and restard again !
i have a stock rom on 4.4.3
any guess ?
i would appreciate if you help me out