try this enter BIOS, go to the last tab "save & exit" and choose "load default settings", press F10 and choose save and exit.
enter BIOS again and check about frozen password, if it's frozen, clear it and press F10, save and exit. check again.
the best thing, it would to clear password, save and exit, take off the HDD, boot to BIOS, save and exit again, put back the HDD and try to boot; but you need to open completly your laptop back cover but....
if you are under warranty, it's not a good thing to do.
try a battery reset too:
https://us.answers.acer.com/app/answers/detail/a_id/34843/~/acer-internal-battery-reset
so, if you are under warranty and can't clear the password, please contact Acer support service.
