As on ongoing process to fixing my lap top...(apple have deleted a few of my previous frustrated posts )....here's what has happened so far.....
After installing high sierra update......macbook pro retina 2015 model started to slow......mouse could barely move...
.....screen glitches started to appear......
12 hours later.....computer can barely operate......even in safe mode.......the screen begins to appear like 'static' on an old TV........impossible to see anything....then it crashes.......
I managed to make a bootable OS X SIERRA SD card to revert to the old OS. After leaving the lap top off, i had a window of time where i could try and use the boot disc to install OS X SIERRA. I gave up last night as the screen kept on going into static glitches and then crashing.....
.....this morning.....i tried again.........and the weird thing was.....the static screen glitching continued as i tried to install SIERRA which.......and after about 20-40% of the install process....the screen glitching suddenly stopped....( which leads me to think that the older OS version of SIERRA has overridden some of the HIGH SIERRA settings and now i have no screen glitch on my lap top...........( YES WEIRD I KNOW ).....
.....BUT ......my ( what was ) a high speed lap top......is now really slow....i can barely move my mouse and it's always frozen..........
....Im trying in safe mode now to install the latest SIERRA updates and to stay AWAY from HIGH SIERRA for now.....
Weird how the screen static has stopped though......usually people say your lap top screen is dead after that...It's obviously something to do with high sierra on 2015 retina MacBooks.......
Im confused......I just want my lap top to work fast again....It's been 24 hours of trying to fix!