Why does my phone get stuck in a boot cycle?

I own an Android DNA.

Couple days ago it did this thing where a prompt popped up saying something like “To restart your phone, keep holding down the power button for 2 seconds.” It wouldn’t let me do anything else. Then the phone turned off and then booted, but then rebooted, and rebooted, and rebooted – and so on. It wouldn’t get past the HTC logo.

Eventually I just kept waiting and pressing the power button and waiting and then it finally stopped.

Now today it happened again. Then it stopped. Then minutes later it did it again. The hell is going on with it? There doesn’t seem to be a particular thing I do to make it stop. I try holding down the power button, other times holding it down with the volume because I heard that works. But then it doesn’t work.

The one thing I noticed is that so far it has happened only when my battery is on the low end, like less than 30%.