Here's another option in a spray can. Go to your hardware store or even Walmart and pick up a can of appliance paint. Only comes in black, white, and tan. If you've never tried it, appliance paint applies easily, flows to a very smooth finish, has great coverage, and is a very nick proof paint...
My Shimano Steps has the same exact problem. The only thing that works is unplugging the display cable and plugging it back in. Quite annoying. Ddid you ever figure out what was wrong?