How did you try to flashback with the file renamed? You can't do it from inside the BIOS, you must use the flashback button on the back panel.
Power off, clear CMOS, then use the BIOS flashback button without powering up. It should flash for a couple of minutes and when it stops flashing you should be good.
You probably already have a FAT32 formatted flash drive with the C6H.CAP so it should just run.
Tired of trolls and mods that act like this platform has no problems and it's the users fault. Later.