It may be the sensitivity on the screen due to the new screen. Try using a different combo of gestures. Correct me if I’m wrong. I never had this phone but I replaced a screen on my otr phone and it’s sensitivity is SUPER high. You don’t have to even touch the screen to have it register the touch. Good luck
Try unscrewing the back of the keyboard and if something is out of place, put it back to where it was. If some springs are broken, order replacements. If nothing is visible that is causing the problem, contact the manufacturer.
Ok. First of all, this is extremely hard to do. You need to invest in the right tools and other things. Next, iPads are WAY more fragile than iPhones. One wrong move and no more iPad. It would be a little bit more expensive taking it to apple, but there would be NO risk. That’s what I recommend.
Make Shure that the paper is being picked up by the guise wheels. If not open it up and check for foreign objects or paper Jams stuck in the way of the paper. Something as small as 4 grains of rice, positioned in the right way can stop everything.