I turned on my camera Canon 6mark2, and the screen just turn like this. And the camera is working no more. The screen continues to look like this after I turn off the power.
Your camera is obviously malfunctioning. You need to take it or send it to a qualified service center to diagnose the problem, provide an estimate (or confirm that it is covered under warranty), and allow you to decide if it's worth fixing or not.
If it's under warranty, you would need to contact the nearest Canon Service Center for instructions on how to get it repaired using the warranty coverage.