Hey folks, I've run into a black screen of death on the rImac on trying to boot up, all I see is a cursor. I've Googled it and tried a lot of what I've read online, holding down shift etc, pram reset or something of the sort, nothing at all works. What's the solution? Would've been nice if all it needed was a simple reinstallation of Yosemite but I wouldn't be able to do that since I have no idea how to, and I've just had this a few days and just yesterday got an Airport TC to backup to but didn't get the chance to do it. Surely there must be a solution.