When boot my macbook pro retina I get a dark screen

I have a MB Pro Retina 2012. currently I can't giv out more information. But the OS software is up to date.

Since 2 days ago my MB has problems rebooting.

I get a black screen with a cursor when it shuts down but needs to be forced to shut down ecerytime. When I restart it. The screen is completely turned off and stays like that even if I log in blindly. So far I did a SMC and PRAM reboot, cleaned the caches but nothing changed. I recently found out that closing the lid after start up to login screen and waiting for it to go in sleep mode and then waking it gets the display working again. BUT the problem with reboot and shut down persists.

I remember updating Windows on my bootcamp partion may be a day or so before, i might not have waited for the update to finish and do not remember if it needed a restart. So i thought I'd try to boot the Windows partion numerous times. Since it didn't seem to work I went to OS system preferences and decided to choose the windows partion as usual start up.

Now I can't do anything. I tried to blindly switch back to OS Partion by holding down the option key on restart. Nothing happens now. I don't know what to do anymore. Can you help me please?