Lenovo IdeaPad 700 bios password

I've had a Lenovo IdeaPad 700 for several years now. After about a year of ownership, it malfunctioned, and I had to send it to warranty technical support. They repaired it (reportedly replacing the HDD) and it worked smoothly for a while. However, when I tried to install Linux, it unexpectedly prompted for a BIOS password that I didn't set. I went back to the store where I purchased it to seek a solution. They assured me they hadn't set a password and contacted warranty technical support as well, who confirmed they hadn't set one either. The only solution they offered was to send it back for

Question by lxlDanilxl on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.