Sudden unexplained failure to boot

This machine suffered from a sudden unexplained failure to boot.

The root cause turned out to be the storage for EFI variables being exhausted.

This was resolved by booting into the UEFI Shell and deleting all the dump variables that had been created. This was done using the dmpstore command.

This will delete all variables with the specified GUID. To determine the GUID to use you can examine all EFI variables with the command