Same thing happened to me. The monitor just went dark. In all likelihood you have a Model AOM78. RV Cam's in Baton Rouge is who I used. I sent them both the camera and monitor for testing. They tested them for free and found that my monitor was bad. It was replaced with a Model VOM78. The entire process took about a week. Here's their website
RVCams Backup Cameras and Rear View Systems: Backup Camera Systems (All) The cost of the new monitor was $202.00 plus shipping. They are excellent people to deal with.
Yes you can remove it. It has two tightening knobs that hold it to a bracket that hangs down under the dash. Very tight fit.
You may want to upgrade to a newer unit but it'll take some modification of the dash area.