What happened when the update failed at 80%?? did your unit boot again??Update: use a HIGH QUALITY flash!!!!!
My first attempt failed about 80% though. It was a SanDisk Cruzer flash. Replaced with a Kingston and resuming.
This is an intense process. Not only is it 4GB of updates, it has to read each file twice. Once to verify and once to install. If the drive overheats, you start over.