mr4-tc sp
First thing I would check is the 25A fuse on the right side of the Protrak. Maybe this has blown for any reason.
Actually the message "Check external Fuse" is saying this. Just replace the fuse and check if the Protrak is working again as it should. I had this happen one time after one of the charging leads touched the output sockets of the powersupply.

If this doesnīt work maybe one of the FETīs has blown or maybe there is a software problem. I had exactly this with my older Protrak but it happened just some days after I bought it. But I have to say I never had a problem with the FETīs.