iMac 2010 black screen after start up
Hi,
I am having trouble with my 2010 iMac.
when I boot up, the computer starts as normal and the after the start up sequence has completed, the High Sierra screen appears momentarily and then the screen goes black.
The computer is still running.
sometimes if you press the power button on the back repeatedly, the screen will flash on for a second but then immediately turn black?
Any ideas what’s causing this or how to fix it?
could it be sleep mode related??
Any help would be greatly appreciated.
Thanks
iMac 27″, macOS 10.13