I'm having the same trouble as the thread starter...but I'm not sure if I'm misunderstanding your suggestion or you're misunderstanding our problem.
I bought my switch used from eBay. The default user/password of admin:admin does not work...nor does the degault guest:guest.
Using your suggestion to restore the password to the switch by hitting ESC, etc...I don't see how communicating with the switch would be possible without first authenticating as a user.
I've got my switch connected via the supplied serial cable to a desktop computer running Windows 2003 Server...I don't know how to proceed from here on.
The default PowerConnect software prompts me for a username and password (which I cannot answer correctly). Via telnet, I don't know how to try to access the switch because I don't know it's IP Address.
Any suggestions are helpful. My particular switch is the PowerConnect 3348.