im having a big issue with my iMac mid 2011, last night the Imac just reboot itself and after that i can't use it.
There is a white screen (see picture), the logo and loading is always there, sometimes the loading dont get to the end and the Imac reboot itself, an eterna loop of reboot.
I tried all methods about how recovery with USB, from Internet, from the recovery partion and nothing works, in fact the OS doesn't load any visual window like OS X Utility.
The thing is that i don't know if this is a hardware problem like HD or if this is a software problem.
I have the MacOS Sierra
Any idea about it?