Tnx Kevin,

No sorry, batteries are fresh, and checked the cable connections too.
It could be an ecu problem as well, because it looks like I can only acces the status screen, but cant go to the other menu's, for runtime and setup.
Still weird that the unit flips back to the start screen, and doesn't work at all after I press the "menu" button. That's until I switch off&on the ecu.