Simrad RD68 Screen failure
I have had this problem.
You can take the front of the unit off after pulling off the control switches and unscrewing the fixing scrws,carefull with the connecting forks when pulling appart.I expect you will find the larger connecting strip connection will be furred up. I cleaned up both connecting surfaces, applied some silicone grease and put back together, now OK.
I would also take out the "O" ring seal between the face and main unit, clean silicone grease again and reassemble.
Hope this helps