Chosen Solution
On startup screen freezes on grey with centre circle with diagonal line. I have tried starting holding various keys as suggested on internet sites - control, option, P and R; C; etc. nothing seems to work. The computer has been quite hot lately. Prob a 2010/2011 model. The power transformer also getting quite hot. Perhaps time for replacement of the lot?
I had this issue with my MBP and it was because the GPU was starting to fail. I would recommend trying to force the intel GPU to run on startup and see if you can get back into MacOS that way by following the steps here:https://forums.macrumors.com/threads/for…
Sounds like your hard drive and/or HD cable is bad. Do you have a friend with a Mac that you can connect yours to? If you do see of you can run Disk Utility from your friends Mac to your attached system. How to Boot a Mac in Target Disk Mode
