Cannot install under UEFI

I am trying to install RHEL 8.2 on a Dell PowerEdge R410.

This server has a problem: UEFI does not "see" the hard drives; BIOS does.

The previous OS was installed and booted on BIOS (not UEFI), so, it was not a problem then.

But now, the only way I can boot from ISO is if I have UEFI boot enabled. And UEFI cannot see the drives.

If I boot with BIOS boot enabled, then I can see the drives in the Boot Menu, but when I select the flash drive as boot device, I get an error message "isolinux.bin missing or corrupt".

I am stuck in a vicious circle. The only way to see the drives is to boot from BIOS, but the ISO doesn't work with BIOS. If I enable UEFI, then I can boot from ISO, but I don't have any drive to install into.

Is there any way to boot from ISO in BIOS boot mode?