Error 4 & 5

Hey Michael John Martin, 

The service manual in the documents section doesn't mention error 4 but for 5 it says

"ER 05: Memory data were rewritten.
Repair measures:
• Check air velocities and save values for S1 to S4 again.
If the failure continues to exist, replace the main PCB (see Section 13.1)."

This looks like the saved flow settings were lost. You'd need your hood balancing service to help you out. There is an auto-calibration mode shown in the manual. But it says that is just to ballpark it and flow will still need to be checked.

Good Luck!