Chosen Solution

Please check the photo below. Is this a failing GPU? If so, this kind of fault seems rare on those Retina 13-inch 2015. I tried to plug an external monitor, and it shows plain grey, nothing else on screen. Would that be solved by reballing? How can I go about this?

Yes, your logic board has died. Sadly, your system does not have dual GPU’s. The Intel CPU has it incorporated within it. Time for a new logic board sorry ;-{ Here’s the IFIXIT guide you’ll need to follow: MacBook Pro 13" Retina Display Early 2015 Logic Board Replacement within the guide you’ll find the possible replacement logic boards.

if you get it reballed would it work? how does it fail?

Same here today. After 1-2 Minutes the Display of my A1502 shows only cryptic artefacts. Could reballing of GPU will fix this problem?