Samsung Galaxy S — Have I bricked the phone?

Decided to root my second hand Samsung S8 + but have managed to get stuck on a screen where I am unable to swipe to unlock.with not a clue on how to get out of it. Touching the power button brings up a big white padlock.

Holding the power button does absolutely nothing and I have no idea how to turn it off.
Holding the power button and volume down gets me to the same screen but without the big white padlock but the phone does not respond to touching or swiping?

Unfortunately being a newbie here I am unable to post screenshots.

My first attempt at rooting so please keep any reply's simple as I do not seem very adept at this black art.

My problem with this is after downloading the correct firmware and putting the files in there correct boxes and pressing start the only thing that happens is on the left side Odin box I have File analysis which is correct below that is setupconnection and then nothing seems to be happening.

I am assuming that this is because I am not in download/recovery mode but stuck on the twrp lock screen?