A computer protected by a BIOS password cannot be unlocked without the password. Dell could help, but you would have to prove that you are the legitimate owner and, if it is out of warranty, you would have to pay for the assistance. If you bought this recently, return it for refund since the vendor sold you a locked and unusable computer. The only other option is a new motherboard. P.S. That system was shipped Dec. 2019 to Netherlands. P.S.P.S. You should not post Service Tag in a public forum, as that can reveal private information. I removed it for you..
I've bought a Dell Latitude 5400 with service tag < Service Tag removed > via a market place website.  Unfortunately the BIOS password is locked and I cannot become the password. Can you help me? What info do you need to know from me?
BIOS password