High Sierra upgrade gets ~40% through and then fails?!

I know it's a dicey laptop, with LOTS of DSDT patches... but this was a strange one. Using MBP11,1 SMBIOS with correct values.

At the point where it stops, it is the standard Apple "Cannot be installed on your computer - diagnosis" message.

Any ideas?

Using Acer V5-573 with SSD 8GB RAM, i7-4500u