Well, I was 99% sure, but the optical drive you mentioned confused me
but since you confirmed that it is the primary master I will retry the sfdndos method
You may also try the newer TSDNDOS. It's part of later TS-L632H firmware updates from Dell. Additionally, switch the Sata controller to AHCI in Bios (plus removing the HDD). Otherwise, there are two primary master drives in the system (at least seen under Windows) which might confuse the flasher. And don't forget to use the "ignore hardware" command line switch
from a bootable DOS disk once more.
You are still able to boot from your optical drive? Or are you using an USB stick?
The front plate is quite easy to remove. There's three clips that you can fiddle with to remove it. They're very delicate though so you need to do it gently.
Thanks, good to know. I never tried to remove the bezel