Vostro 3888 WITHOUT UEFI and Legacy Boot option

Purchased 3 Dell Vostro 3888 i5 for office use. Ubuntu Linux. Installed Windows 10 on 1 PC. Successful. Bios Version 1.2.0

Upgraded BIOS on 2 other PCs with Ubuntu Linux. Unable to install Windows 10, sometimes it says, no boot disk found.

I am following with Dell technical team on the Whatsapp since 3rd Jan. 2021. This particular model doesn't come with UEFI and Legacy boot option as per them.