I ran into the same problem too. The dashboard went blank after I hit install, and I let it run for a good five or ten minutes. Then I came here and read that wygnoyes had that happen, stopped it and the site was upgraded to 2.7.1
My blog now says 2.7.1 and everything seems to be working, but I’m a little worried that I didn’t get any kind of confirmation that it all went through alright. I really don’t want to have to do a manual upgrade, I hate upgrades as it is.