I have a 2012 Mac that time to time get stuck in the loading screen or get a infinite white screen.
Cuz of that i already formated it 3 times, so now I'll make a guide of how to format your Mac Book. For everyone that needs it and for me who everytime that need to format again need to re-search everything another time cuz already forgot how to do it.
Anyway, lets go to the how to do everything that Mac says for you to do, and some others.
To Apple, the circle with a line through it, the Mac starts up to an Apple logo progress bar, the blank screen and probably some others is solved by macOS Recovery (press power button for 10s until your mac turns off then turn on and hold cmd + R). Then you repair your disk with the Disk Utility, if it don't work reinstall the macOS.