1st thing to attempt, which it sounds like you tried already, is holding down the power button for 15-30 seconds. This should automatically reboot the device. If, however, this does not work...
2nd thing you can try is hold down the power button until you feel the phone vibrate which, if you have the vibration setting is turned off on your phone, is about 2-3 seconds. The image attached shows what would be showing up on your screen if it wasn't dark. Try and tap on the "Restart" button that is on the bottom left of the middle box on the screen... roughly 1/4 inch down from the middle and 1 inch from the far right of the screen.
3rd thing you can try is plugging the phone into the charger and letting it charge for 5-10 minutes and then repeating steps 1 and 2 above.
4th thing you can try is using 2 or 3 fingers and, starting from the bottom of the phone, tapping the phone hard all the way up and around the screen. Sometimes (though extremely rarely) there may be a small "something" that somehow got jarred loose or repositioned in the phone and this may help knock it back into place.
I've also heard people havingg success actually putting the phone in the freezer for 15-20 minutes and then re-attempting steps 1-4 until something works. This may have to be for when water gets into the device and the freezer thus turns the liquid into a solid which thus wouldn't hinder (as much) the liquid from affecting the internals of the device however I'm not 100% sure as to why this method might help outside this scenario.
Now, as to WHY that happened?? That's extremely hard to tell. software glitches. hardware glitches. outside humidity, temperature, any magnets it may come into contact with, dust that has gotten inside the device, etc can affect it and cause it to act strangely.
Hope one of these options works for you. If not, please reach out to us directly via support@mark37.com and we'll initiate the process of having you return the device to us and shipping you a new one.
