SamyGO

I have a 40 inches H6670 Smart TV upgraded to the latest firmware on the Samsung website, that is, T-MST14DEUC v2890.2. The auto update in the Smart TV said the v2880 was the latest firmware before upgrading via USB.
I noticed that the guide here for downgrading is from three years ago and the v2890 update is from last year, so I was wondering if I can still downgrade down to v0000 for rooting it or it would brick.

If your tv accepts 0000 firmware, then it should downgrade. If not, then means you are to late.

Thanks but how can I be sure that my tv accepts it?
Is it safe to try to downgrade then?

If it starts software upgrade procedure with your given firmware, then means it accepts it. If it says no software upgrade found then means it does not accept it

Thanks for the reply, I tried downgrading and it did, so I can confirm that downgrading a H6670 to T-MST14DEUC v0000 works perfectly fine.
Now that I successfully downgraded I should re-upgrade to a firmware version T-MST14DEUC <= v2130, right? So can I install v2130 now?