What going on everyone, I am new to Mac world and I am very happy with my 2015 macbook pro. But I was trying to tinker with the dual boot option by booting Ubuntu through usb on my mac. It gave me 2 options, first was to boot through the ISO and the second it was asking me to edit the code. I naturally select first option and did not read the next prompt and hit a key. The result was an error which I thought it would be a good idea to reboot. When I rebooted the screen went black and nothing happen and it been like that. Has anyone experience this type of problem and why does it do that, as well is their a way to bring back El Capitan OS.