Coloured bars on screen on startup. Doesn't power external keyboard.
Good day everyone,
My relatives have this 27" imac they were using up until it randomly started displaying coloured bars on the screen. I have since been attempting to diagnose this (With a trusty ifixit kit and some PC knowledge), but nothing has availed and it remains this way. I tried plugging in a USB keyboard but it does not receive power (AKA the caps lock and all other functions don't work) yet plugging in my samsung SSD it powers just fine over the USB ports but it doesn't show data reading. Trying different combos such as unplugging, holding pwr button, plugging in whilst holding pwr button, letting go and turning on have led to Full tilt fan spin (I don't know what this actually does. does anyone know what it does?)., it reveals the same result.
Heck, I even went to the effort of taking it apart to inspect the graphics card but that unveiled absolutely...................nothing. That means that this imac was gonna be ewaste in council cleanup but i said no so i took it home and am now running a few tests on it. This imac is one w Mini DP and firewire which really sucks because I have a dell S2722QC which is HDMi and USB-C only so i can't really get it to work on this display, however i do plan to buy an adapter to see if it boots onto an external display. This yielded nothing but black screen on both a 4k dell and a TV
Hopefully you guys are able to figure this out as my research has shown no one else has had this issue. I am suspecting graphics card failure but it could be one of the connectors. Note: i took it apart after it was like this and put it back together to find it in the same state.
My imac 27" is EMC 2390 yet looks like the previous model with it's graphics heatsink. Which set of guides should i follow?