mobile

I accidentally flashed the CF Autoroot of Note 2 (gtn7100) in my Galaxy s3 (gti9300) in an attempt to root my phone.
After booting up, everything is working fine except touch (the volume keys, power key, display, screen rotation, bottom buttons are working fine). Touch screen is not working. I flashed stock rom via odin but none of these saved my device. So I confirmed that its a hardware problem. I don't know much about hardware so im asking this..

I went to the repair shop and they just looked at it and said i have to replace the whole LCD Display + touch. There is nothing wrong with the Display, then why it needs to be replaced? (I couldn't ask them then:mad:)
Is my device's touch completely gone? What should i replace? Full touch screen and LCD display?
Or the digitizer?
If you could or if there is, can you give me a link to what is to be replaced?