SamyGO

1. Did FFB finish its job, TV restarted or you did restart by hand?
2. How long was FFB working until restart?
3. Did you anything before (other method) to restore firmware before you managed to use FFB?
4. Did you add u-boot.bin, Image and fnw.bin to FirmwareUpgradeUSB?
5. I guess, you able to navigate menu, but you do not see any letters? if yes, you can do firmware upgrade from menu (blind navigation to upgrade menu)

Do you have ExLink cable? if not, take care to solder one, i think, you will need it to restore TV.

Is watchdog in service menu OFF and debug is on? Ok, then you have an insurance to restore TV over ExLink cable.
In which firmware? try to the same 3000.G
You got problem because of unsuccessful use alternative firmware activation before. On russian forum was one TV (B650) with the same problem. Tv has been broken totally and just ex-link did help (everything went well).

Definitely you needed to build/buy ExLink cable first.

Attach firmware upgrade USB with firmware (3000.G or other)
Navigate to start firmware upgrade. Try few times if you do not succes to start it. Wait and pray...

If you do not get success, solder ExLink cable, i tell you what should you do next. (get the cable at first)

Congratulations
Realy, 3001.1 is the old firmware? I think, it is after-februar firmware...