I had the exact same happen to me when upgrading to 360 on my V6 box, no upgrade option on the Home Screen so called VM, whatever they did caused a M63 error code despite 5 follow up calls they have been unable to help and I have to wait a week for an engineer visit
Than you for your post regarding the M63 fault you are experiencing following upgrading to TV360. I am so sorry that this error has occured.
I am glad to hear that you have an engineer appointment booked to get this resolved, apologies for the delay in getting your TV services back up and running. Please do keep us updated with how things go with your engineer appointment.