Nexus 5 is not turning on.

A

AC Question

Today morning i flashed Lineage OS 14.1 on my Nexus 5. Everything was working fine until now while i was pressing back when using ShareIt app, it got stuck on a black display. i pressed back button, the button got highlighted as usual when we press back, but the highlight stayed there. I waited for some time and then tried to press and hold power button, but nothing happened. Now it got switched off automatically, and is not turning of. I connected it to charger, but it is not even showing charging display. Help, What can i do now?