Unable to unlock/turn on Nexus 4 : Lollipop 5.0.1
I have experienced many problems with Android 5 on both my Nexus 4 and my wife's exactly identical Nexus 4. Strangely enough, both phones experienced slightly different problems. The main issue with my own phone was WiFi - it simply did not work except for a few hour period after rebooting.

I have not experienced this issue since switching to Cyanogenmod using the instructions from their Wiki:

http://wiki.cyanogenmod.org/w/Install_CM_for_mako

My wife's phone has experienced the same exact problem as you. Sometimes it won't show anything on the screen, won't wake up. After rebooting everything is fine. This occurs even when plugged in and fully 100% recharged.

So my solution is to get away from Android 5 Lollipop. I don't know how to downgrade to an older version of Android, but moving to Cyanogenmod has fixed my own phone and I will be switching my wife over probably this evening.