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.
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.