Post originale di: Dan ,
You’ll need to see if you can access your system from a second Mac using screen sharing when you loose the display. Are you abel to get to it? If you can’t you’ll need to run diagnostics holding the '''D''' key when your restart the system. Then check the onboard diagnostic LED’s reference: [https://support.apple.com/en-us/HT201255|Mac startup key combinations] I wouldn’t refresh the thermal paste quite yet.