I was having the same issue and was able to fix it by holding down the [FUNC] key while powering up and then pressing trig1, as suggested by @tnussb above. Then I turned off the device, and back on.
Then I noticed that the “pin” to remove the memory card was sticking out, so I turned off the device, pressed the pin, re-inserted the memory card, and turned the device back on.
This sequence of steps fixed it for me, not sure exactly which one. Maybe this will be of help to others.