Motorola KRZR black screen

This URL explains that the blank screen is caused by a loose cable, includes instructions, and includes another URL that shows how to take the phone apart and re-seat the cable: http://www.howardforums.com/archive/topic/963501-1.html

I just fixed mine. The cable goes from the back of the phone (below the battery and SIM card) around the hinge and connects again on the flip-up part, under the screen. Re-seating at the main unit didn't fix it for me (dang), so I had to take off the cover on the flip-up part. Pretty hairy, but doable. You'll need TORX #5 and #6 screwdrivers.

I also saw where local repair shops will fix it for $75 (ouch), but that may be for a screen replacement--which is probably not needed. Opening and closing the phone is what causes the (tiny, flat) cable to need re-seating.