With this kind of product there will typically not be any way in to the product without either the correct password or a reset-to-factory-defaults... that would be a security flaw...
The manual for the NBX 100 (found it online) specifically says that there is no backdoor password...
It seems to me quite likely that even if 3Com were willing to help you the best they could do would be to reset your unit, which isn't what you want... I take it that webpage I linked to was no help (or your firmware version too recent??)
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