My DNA is about 13 months old, never rooted, never messed much with settings etc.
I picked my phone up and my screen was on with a blacked out text box that said something to the effect off 'press the power button on 1 second to reboot'. Before I could process what I read, my phone shut off and has been in a "boot loop" since.
I have read everything I could find and finally decided to create an account and ask here.
I can get to the "Boot" screen by holding the power + Volume down buttons. If I press the volume down button again to select something, it immediately restarts the boot loop. If I do not attempt to select anything, I'm able to buy a couple useless seconds before it begins again.
I'm unsure what to do about it, and I of course have nothing backed up from the past 13 months (like a shameful idiot).
I managed to USB my phone during the extra second I got when in the Boot menu. Forced it to switch to USB Boot menu. From there I was able to fully power off my phone. I left it alone for ten minutes, and it turned on like normal. Nothing lost, no recovery mode, no factory reset!
I decided to post the solution here to help those who have the same problem.