You'd have to check your manual for what the message actually means, but the most likely thing is that it can't talk to the controller. That's usually a connection failure anywhere between them, usually at the actual connector, but can be anywhere in the wiring.
Generically, with display/controller systems, when the display and controller can't talk, the controller often starts up in whatever it's factory default mode is, which is usually the lowest possible level. Each system can be different, so can't say if this is how yours works.
Visually check the entire wiring of the bike in direct sunlight for best visibility. Any marks or damage or sharp bends to the cabling, etc., may warrant other tests.
The connector you can check first by unplugging and examining both pins and holes in direct sunlight for best visibility. If you don't see anything, just plug it back in, and see if it works now. Unplug and replug several times if it doesn't, and if that still doesn't fix it, then you can get out a multimeter and start checking wire resistance between each pin and wherever the other end of that wire is, inside whichever device the cable goes to.
(many devices on bikes are glued or ultrasonically welded shut for waterproofing, so opening them up wwill remove that waterproofing and may break the casing and/or parts inside).
If there was any event that happened prior to this problem starting, I'd recommend checking things that event could have affected. (crashes, rain, overheating, vandals, modifications, setup changes, etc).
BTW, I recommend you edit the title of your first post to reflect what you actually need, or what the problem is, so that those that can help with that specfic thing are more likely to read your thread.
