I have not had to reset mine since but here is the info I used to reset it:
Re: Reset Admin Password
I have the same problem.
I setup a new access point, changed my SSID. Went to the admin page to set the new SSID in the 6515 and didn't remember the password. Looked on the net for it and found it's supposed to be either 1111 or the SN of the unit. I tried both and neither got me in. I did the full factory restore which I thought was supposed to reset the password to the 1111 or SN. None of them work. I did a factory restore about 6 times over the weekend and the password doesn't work.
I remember when I first got the printer the password was 1111. I changed it to Admin a long time ago.
Can I get help on this? The printer is about 2 years old and I do not have any maintenance. I don't see any reason to have a maintenance plan on a $400-$500 printer.
That was all the info I could find on the password.
I forget the prompts in the menue it's been a few months since I reset mine, do make sure you read all the prompts my guess is the wording might be differant in the menue so go through it carefully.
or it did not like the pasword you made for some reason think I recall it having to be so long and being picky on what was entered.