Updating BIOS A03 to A05 on Aurora R4 gets 'Error: Problem allocating memory'

I recently bought a new GPU which requires me to update my BIOS as it turns out my Aurora R4 is on an ancient BIOS even though I only bought it 6 or so years ago... Over the last few days I've learnt more than I ever wanted to about this process, but am stuck at near the final stage. 

I've learnt I need to format a small USB flash drive to be FAT32 (I kept recommended cluster size and used Rufus after the Dell utility formatter didn't seem to work), add the Aurora R4 BIOS A05 update .exe file to it, load in Legacy mode and then boot from the .exe BIOS file. It seems to like it, ME systems are the same, it notes I am on A03 and the file on the stick is A05 then I hit this roadblock:

"start to update new bios... - Error: problem allocating memory

remove temporary files... OK?

reboot system or not. (y) yes. (n) no."

Any ideas what I may have done wrong would be really appreciated