Crashing if not plugged into a monitor

[mistletoes]

I have a mid 2015 15 inch pro.

It keeps turning off after 3-12 mins of use (plugged in or not)

If I plug it into my monitor on my desk (power plugged in or power unplugged) then it works fine.

I have the monitor plugged in with a lightning adapter (Samsung curved monitor)

Could anyone point me in the right direction... hopefully not the garbage can :/

 

[UncleBillVT]

It sounds like a thermal issue if the system has to warm up for a while before it faults out.

Question, is the system actually shutting down or is it still running but not showing any display on the built-in LCD?

What happens if you plug the external monitor in when it faults out?