Ok, so I did the most stupid thing ever. For some reason I though I could beat the battery time while installing an update on my Macbook Pro to 10.10.5 or so. Of course, computer died with just 5% left of the installation and I'm pretty angry with myself. Just a bit. So, I've tried starting the computer in recovery mode, to repair, verify permissions and all of that with no success. I've tried erasing the hard drive to install Yosemite all over again, no success. I tried to reinstall Yosemite straight from the recover menu, also with no success. I've now started my new macbook pro through my old one (target mode), just to access the drives in disk utility but still the same thing. Could anyone please help?