Thank you for using the Support Forum. I found this explanation for the Fault Code 91,720.00. You also mentioned that the machine is power cycling. Please take a look at this solution for power cycling and see if you can perform the steps. If not please consider contacting your support centre for further assistance.
If those suggestions does not work, try starting the machine with the network cable unplugged and see if that helps. Let the machine take its time, around 20-30 minutes.