Intermittent digitiser after replacing Screen and Battery

Hi

I had to replace the screen on my 18month old iPhone XS Max after the OE battery swelled and cracked it from the rear. The screen was still functioning (including the digitiser, but the LCD started to bleed.

I replaced it with an OEM screen and the battery with an aftermarket battery. I transferred the serials from the old components to the new ones and the features such as True Tone and 3D Touch appear to work ok, but the battery is showing “Service” but functions as the original did when new.

The issue I am getting is that the digitiser intermittently freezes and I have to lock and unlock the phone. Even this only works 50% of the time and I find that squeezing the screen around the edge (as though trying to re-seal the glue) and then lock/unlock works.

I have tried a third OEM screen and this as the same problem so I am perplexed as to what it the cause of the issue?

When replacing the components (which I have done on about 50 friends and families devices over the years) I always unplug the battery first as I know that there are some sensitive capacitors, etc that can ‘fry’ themselves or adjacent components of not powered down but feel that the issue might be something of this nature that is maybe causing the problem even though I have never experienced an issue of this type every before.

Does anyone have any ideas of the cause of the problem as it’s very annoying and frustrating?

Many thanks in advance for any assistance you can provide

Ash