My Nexus 5 is frozen. How can I fix it?

[AC Question]

My nexus 5 is frozen.

The screen keeps flashing Google. I have tried pressing on button at the same time as Volume down button. A screen with a Start button appears, but does not respond when I press it.

 

[belodion]

My nexus 5 is frozen.

Power off the device. Then hold Power and Volume Down. From there use the Volume rocker to choose Recovery. Press Power once. When you see No Command, hold Power, press Volume Up once, and release both. Use the Volume rocker to highlight Wipe Cache Partition, and press Power once. Agree to any warnings. Note that on a Nexus 5, the wipe takes 5min or so.
If still no go, get back to us.