SamyGO

I think you need some brain.

Thanks for report.
Writing this i wanted to say, all models and firmwares are listed in Supported models section. And your TV model is listed as First:

SUPPORTED TV MODELS ONLY:

LCD
LExxB65x - firmware: T-CHL7DEUC
LExxB75x - firmware: T-CHL7DEUC

Also step 4 says:

4. Download "pre-FEB" firmware for your TV (original only!). Some firmwares on opensource.samsung.com:

T-CHU7DEUC-3000.G

If you don`t find firmwares, ask on forum

So. My apologize. I don`t change my IMO. It was a joke and seems you haven`t understood this.
I think you should say thanks to me, you had 200% chance to brick TV, instead of making reports

Good luck.

Seems here is some problem with Image file. Please redownload, check checksums and try FFB again.

You can use SamyGo All Extensions for that, please check B series wiki. You have to enable required plugin before to start extensions. Also configure it before

Go to service menu and set OTN support OFF.
(Control-SubOption-OTN)