Cannot restore to default, fails at 65%

After experiencing issues with performance I tried to refresh the T100. After doing so it reported it had not completed successfully . I then tried a reset when done it also said it encountered issues. I then tried a factory reset and it runs to 65% and stops with 'There is a problem resetting your PC'. I tried three times to do this with the same result.

I've call Tech Support and no resolution, but did give me an RMA, System is still under warranty, but will it cost me to repair? No damage to the system and not outside applications were installed.

Please help to resolve or at least put my mind at ease as to cost.

Thanks in advance