Chosen Solution
Replaced the digitiser after daughter cracked the screen, worked fine at first (although I didn’t test the responsiveness of the entire screen - assumed if you could unlock the device with a PIN, open some apps, it was good). About a week later it seems to behave sporadically (either sometime not respond or open random apps / type random characters). Seems worse one horizontal orientation that the other. This was an aftermarket replace, could that be the cause? Thanks
Poor quality aftermarket digitizers could certainly cause this. Some of the cheap ones suffer from ghost touching as well. It could also just be improperly connected or you may have kinked the flex when you did the repair. Lesson learned, always check the entire surface of the digi before sealing it with adhesive :>) Take a look at the ones iFixit sells, they are good quality.
Maybe you have a defective screen but before ordering another check if putting pressure on the bottom part of the screen left and right of the Home button. If this causes your screen to touch by himself the solution would be to put some tape on the little components marked with red and tape also the bottom part marked in green.
Sow you have some component on the home button flex which are not always isolated, the little cercle.
And sometimes you have the bottom part of the digitiser showing the lines which go to a segment of the digitiser that need isolation also.
Thanks for the advice, I tried covering the areas mentioned with tape but no improvement (pictures below). Purchased another screen which is now installed & seems to be working well, lets hope it lasts.
