What do I do when my Android phone is stuck on a screen saying "select boot mode" but not allowing me to use the volume buttons to select anything?

I have a Cloud Mobile Stratus C7 and the device at first was dead so I plugged it up before powering it on. Once I did, it began showing a screen saying "Select boot mode" with the options recovery mode, fastboot mode, and normal mode. It tells me to use the volume keys to select, but the arrow is moving on its own and the screen keeps turning on and off. I've searched online but nothing seems to be helping. Any advice?