recently I have had a rather odd issue concerning the MacBook Pro 13 inch (early 2015) where it would crash after being unused for periods of 60-80 min when connected with a DisplayPort Cable to an external 4K display. It was plugged in every instance where it would crash. Additionally, when I disconnected the DisplayPort Cable and opened up the MacBook to use its normal display, it showed a black screen. However, the trackpad appeared the show functionality, but using the screen and keyboard brightness buttons yielded no responses.
Any ideas as to why?