I tried the "remove all power" tricks mentioned above (also mentioned in many places on the Internet), and they did not work for my CF-29 Mk3 (Model CF-29HTM50BM). What did work for me was upgrading the Embedded Controller and BIOS firmware from a pair of diskettes as mentioned in this thread from Victor at AllService (https://www.allservice.ro/forum/viewtopic.php?t=1046). Download the files CF29-EC.rar and CF29-BIOS.rar from the links in the thread, create the pair of bootable diskettes, upgrade the EC firmware first, then the BIOS firmware -- at this point my BIOS password was removed. I went into the BIOS settings and disabled the password at boot.
Now, will this same procedure work for you? Maybe -- my EC and BIOS were downlevel, so the bootable diskettes did have to perform an upgrade, maybe that's required.