Hello, this is Emily.
I assisted you yesterday and advised that this issue should be directed to Dell. The BIOS is the motherboard firmware and is independent of Windows, so only Dell can provide the appropriate support. If Dell is unable to assist, no other sources will be able to. Additionally, if anyone from a Windows forum attempts to help by bypassing Dell's security measures, it would be a violation of our community's code of conduct and considered tampering.
I am sorry, you will hav to keep working with Dell until they approve your proof of ownership. This is not a Windows or Microsoft issue. Sorry.