HP Pavilion ZE4600 Power on Password

I am working on a laptop for a friend of mine he bought used. It came
with a power on password and drivelock password. I went into the BIOS
and used the option to reset the password for the admin and also for
the drivelock. I entered the old passwords for each and in the new
password and confirm password field I just hit the Enter key. Now the
power on password won't accept the enter key (blank field) or the old
password. I cannot access floppy drive or bios as it comes on as soon
as the POST test completes. I have disassembled the laptop and removed
the CMOS battery but I have heard the passwords are stored in a
security chip on the mobo. Is there any way to reset this password, get
ahold of the admin password, or short out the password chip, resetting
the security chip? I tried to call HP, but as I looked at the bottom of
the laptop, the serial number label is gone. The guy my friend bought
it from claims it is not "hot" but cannot provide the original manual
or the label with the s/n (very fishy). HP cannot do anything without a
s/n unfortunately. Any help would be appreciated.