Does not boot, but makes noises and vibrates.

When trying to fit my Nexus 5 into a holder, the power button and volume were accidentally pushed simultaneously and the screen came on briefly, as if only the power button was pushed to wake it up. The phone went dead and I can not re-boot it.

I have followed most of the suggestions I found on this, but I see nothing happening on the screen.

When I push the volume and power buttons for an extended time it produces short bursts of vibrations every few seconds.

I have also heard some short beeps but nothing on the screen