Very interesting. These instructions are completely wrong! Notice the Known Issues list at the bottom of the doc. Those instructions are only for 2k8... I suspect UAC crap. The main part of the instructions should be just like the instructions for 4.1.6 MRs. Go look at those instructions and follow them for this.
Even still, you should be logged into the server as your besadmin account when installing an MR or SP for that matter. I see how you thought that you could use just any old admin creds...
At this point, I am not sure if you should log back in and run the mr again as besadmin to see if that changes the services or just manually change them back the appropriate user in each service.
Actually maybe you have said you already got up running again.