Not a good aaahh?! You might even go one step further if you don't have a lot on the drive at the moment and simply slap a fresh install of 10 if you can get that install.esd converted into a bootable iso image that is! You would still need to see those BT and possibly WS folders intact on the drive however to get that out before Disk Cleanup tool time! The upgrades to repair with the newer builds however wouldn't nothing close to the problematic upgrades initially seen with the 10240 and 10565 builds however.
Did you remember to unplug any addition drives or devices as well as any unnecessary startups to see if something loading up with Windows is getting in the way?