Touch Screen stopped working

4 things need checking when touch-screen stops working:

1/ Software issues: you ruled it out since you did a hard-reboot. As an extra measure, you can restore from DFU mode: back-up your data since it will be wiped. Then press and hold Home Button + Power Button for 12 seconds, then release the Power Button but keep pressing the Home Button for 15 seconds. Then connect to the latest version of iTunes on your computer. It should tell you that it detected a device in Restore Mode (if not, goole how it's done and repeat). Accept the prompt to download and restore your iPad, and leave it connected until it's done. I doubt it will help but since it costs nothing, you can try it.

2/ The touch-screen connectors need re-seating on the logic board. Since you already put in a new touch-screen, your ruled out this possibility. You also in principle ruled out possibility #3:

3/ The touch-screen has gone bad and need replacing; note that the replacement touch-screen that you used could've been defective and/or damaged during installation (too much pulling on the flex cable). To be on the safe side, you can try using another known good touch-screen (no need to seal it in to test). And don't forget that the battery connector must be disconnected first before the LCD and touch-screen connectors!

4/ The circuit responsible for the touch function on the logic-board broke down. You will need micro-soledring skills, the right tools, and experience in trouble-shooting and repairing this kind of circuits.