17.5.14 MR-14-1 to 18.0.3 MR-3 failed

I have a Sophos XG Home box and I'm trying to do the upgrade. The console just hangs for a while trying to book the 18.03 image and then reboots to the 17.5 image. I have tried a few times and just get the same result. I sits there for at least five minutes trying to boot the 18.03 image with no errors showing on the screen. I can't find any error messages and, as I said, none show up on the screen. The box has 8GB of RAM and just an old Dell i5 machine I'm re-purposing. I wish I could give more info but I've searched through the logs and don't see anything related to the upgrade.

Any help would be appreciated. Even if it's pointing me to a log file I can review.

Thanks