this is going to sound really stupid, but did you unplug it and plug it back in? I have run into this problem a couple of times in my line of work, and it has worked for me! "sometimes"
That's the first thing I did. Then I unplugged it for 10 minutes when it didn't work. Then over night. To my surprise, it still didn't work in the morning.
What are these mojavas I keep hearing so much about?