Open the chassis and remove the coin-cell battery for 5 minutes to reset BIOS settings (note: this rarely removes power-on passwords on newer models).
Because the tool is an optical disc image. However, since few people use DVDs anymore, you will typically write this ISO to a using tools like Rufus or BalenaEtcher. The name is a legacy holdover from the early 2000s. dellbiosresetiso