DPC3939B reset button was ineffectual

The following sequence of events isn't making sense to me

• Discovered that my custom password on the DPC3939B gateway did not work.
• Decided to try to reset to factory settings using the reset button.
• Tried the reset button (following exactly instructions from the Cisco PDF file) and the factory default password didn't work.
• Repeated the reset button procedure. Still no go.

THEN, I read a hint on these forums that ,DPC3939B may be rejecting login even with correct password, because I was passing through my VPN appliance (which is between my LAN and DPC3939B). It is said to be a security feature. So...

• Removed my VPN appliance from the picture, gave my  PC a static address, and declared a gateway address corrsponding to DPC3939B.
• Connected PC directly to DPC3939B.
• Success. I was able to login.

BUT...  but...  when I was able to login, I was NOT using  the default password, it was using my secret password that I had tried to get rid of. The default password still did not work. Recall that I had operated the reset button. Twice.

My point being,  the reset button did NOT reset the password. Beyond any doubt, I followed instructions and the DPC3939B did restart on its own both times.  So what is going on?