why not be more clear as to when a PW is asked
windows login screen?
what do you mean no battery the big one, its not needed to run on AC line power ever.
or the HP RTC coin cell inside. (coin sized, tiny)
lacking the RTC battery that kills dead BIOS.
a first order problem that
so put one in, if missing coin, first. 2.9v below that is bad.
3.3vdc is par value fresh battery.
page 39 in the manual tells you how to erase the PW bios.
there are 3 power sources.
LIne AC (remove it)
main huge battery remove it.
remove the coin cell.
push the power on, while 100% dead, this helps discharge more things.
wait 15min or even more even 1hr might help.
put the coin cell back first (its under the memory stick bank)
the PC is 10 years old now.
so leave the huge battery out until the PC runs perfectly ok
as most 10 year old huge batteries are now dead or worse shorted. same with the coin cell they do not last 10 years over.
then get bios working next.
power on with AC only pack and get the text working
F10 = ROM Based Setup"
when you see that hit F10 hammer it.
go in to bios and set default settings now
exist and save then boot the HDD.
see if windows works. if windows.