This fix didn’t work for my MacBook Pro Late 2012 although the symptoms are the exact same. I am guessing the mainboard is bad, possibly the GPU. The built in diagnostics all pass yet it just boots up to a solid gray screen after the initial Apple logo is displayed. Occasionally it will turn to a blue screen with vertical black lines in the screen. Internet recovery also stalls out and goes to a solid gray screen, even when using a hard wired ethernet connection.
