I have a CGE which, I think, is similar to the CGEM and get these messages every now and again. It is usually the RA/Dec cables between the mount controller and the motors which are pretty rubbish. If you disconnect/reconnect the connectors it often works or give them a spray with some switch cleaner like Servisol. I think it is unlikely to be the main board. Much more likely to be a bad connection somewhere.
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