XPS 15 9570 black screen and power issue

I have purchased a "new" second hand XPS 15. Got it home and connected it to power turned on. Keypad lights come on but no screen. Pressed D and power I get a flashing green blue, white, and black screen. Can't safe mode with f2 as no display. Have tried an external screen, same issue. Also when the XPS keys are on, not connected to power and i press and hold the power key, fans kick in and it turns off but after a few seconds it powers up again still no screen. So frustrating.

I see that the technical support team have booked an onsite service to replace the motherboard and RAM to fix the issue.
DELL-Cares