1. Put windows 8 back on.http://linxtablet.co.uk/viewtopic.php?f=35&t=890
2. Back up - just in case you get the same issue again.
Make a recovery image in windows - loads of posts here on that.
I'd also suggest trying macrium free. I've backed up and restored successfully on a linx 8 - nobody's reported it restoring on a 7 yet but there's no reason it shouldn't work.
3. Do the upgrade again.