I'm going to try to keep this as simple as possible as I don't really know what I did wrong or how I ended up where I am now.
I have a Samsung Galaxy S8+ running Android 7.0 and I decided to root it. I decided to follow this guy's instructions on how to do it: https://www.youtube.com/watch?v=eh-I4uxAmUY
I follow his steps and am bought to the "Unmodified System Partition" menu after having gone through the process of factory resetting, wiping my data and using Odin to flash twrp-3.1.0-r1_dreamlteks.
The problem is that now the touch screen is unresponsive. It does literally nothing.
I am stuck at the screen that says "Keep System Read only?" where I have to "Swipe to Unlock Modifications", but find myself unable to do so because my touch screen doesn't let me swipe!
So now I'm panicking: Firstly, I can't get the phone to shut down. Holding the power button does nothing, even if I hold it for a full minute. Secondly, I can't boot the phone into anything except this unresponsive TWRP thing. Thirdly, my computer no longer recognizes my phone when I try to connect it via USB (might be unrelated?).
Is my phone just bricked now?
Can I save this rooting attempt in any way, or at least revert to the stock?
Will bringing the phone to a retailer help me in any way, or have I already broken the warranty?
UPDATE 1: RMarkwald has bought it to my attention that I need to revert back to stock, but I am not sure I understand how to do so from my current situation, being locked at the TWRP-screen and all. Any information on the topic in future replies is deeply appreciated.