My Nexus 5 is only working when it is charging what could be the issue

[Shifas P]

my phone is lg nexus 5 it is only working when i charging the phone when i unplug from charging the phone automatically turns off.
now iam doing reset phone by factory default settings but its taking very long .
what could be the issue??

 

[B. Diddy]

Welcome to Android Central! The battery has probably failed. You'd have to get it replaced.