There is not a solution that resolves all problems. Some people can't get into Firmware Programming Mode, some used hacked installs, some have problems with Metal detection, some have corrupted EFI partition, etc.OK i will search in the 27 pages
You have to find what your problem really is, I tried to put most info into the first post and to give pointers to people troubleshoot, but I can't give a solution that works for everyone. Read the thread, you will find something that will help you.