Oh wow! Any luck? I'm having a similar problem with my girlfriend's Nexus 4.
Quick background:
Her N4 was running well on stock 5.1.1. She then broke the screen which she replaced. Unfortunately she then ran into the proximity sensor issues many N4 users encounter after replacing the screen. She had the proximity sensor removed while we ordered a new one (later realised that the sensor could have been adjusted with tape which may have solved the issue), and started up the phone...which stared well, but then shut off and went into bootloop (well...stuck on the swirly dots animation).
Since then, I have been unable to get the phone to boot...always being stuck on the boot-up animation. I wiped cache and factory reset from recovery and earlier today I flashed the 5.1.1 factory image, each time to no avail! After flashing the factory image today, it was stuck on the boot animation for over one hour. I turned it off and just flashed the factory image again, hoping that it would actually boot.
NOTE: The proximity sensor is still out, since it was taken out by a friend who has the tools to take apart the phone. Could this be the source of the problems?
