Basically, you've bricked the BIOS. THe chip is corrupted and theres no way to boot off of it.
Check your PC/Mobo manual to see if there is a recovery option, such as a USB flashback stick (you put the BIOS file on a USB stick, press a flashbak button on your mobo and it resets it) or a backup BIOS chip.
If not, you need to send it off back to dell if it's not so old that they wont repair it, but you will have to pay for it as upgrading parts normally voids warranties, or get a new motherboard.
I'm afraid I don't know of any less drastic options, sorry