Weird touchscreen behaviour after home button replacement

There are 2 things that come to mind that may have caused this, if this is the first time your screen assembly has been removed there would have been adhesive holding the screen at the top by the ear speaker and at the bottom by the home button, to get the screen released from the adhesive requires a level of prying with a tool and tends to flex the LCD which can result in damaging it as it responds very poorly to being flexed in the smallest way, the other thing would be when you were threading the LCD Digitizer ribbon cables back in the Steele frame, its easy to bend the cables and not even realize it untill you try to plug them back onto the motherboard and by that time the damage is done, either way if one of these things are the problem sadly enough the screen assembly would need to be replaced, for the future if you would warm up the adhesive with a heat gun or blow dryer at the top and bottom of the screen assembly before trying to pry it off it will help dramatically in releasing it.