screen replacement had made touch screen jumpy

So here it is, yesterday I replaced the charger/headphone part of my brothers ex Iphone 5s, as well as the screen. It wouldnt charge and the screen didnt work at all.

So did it, and everything screen wise was perfect. No problems. The phones headphones and loud speaker wouldn't work so i decided to replace the original part after cleaning out the dock (hole?) asit gets filled with dust and could be the reason why the original didn't work in the first place.

So I do it all over again. Loudspeaker and headphones now work like a beaut, and it charges perfectly BUT, and its a BIG BUT...

The touch screen doesn't properly work. It has its moments of perfection, but then starts to jump around / won't respond to touch etc. Its quite weird.

Tried reconnecting the LCD/Digitiser and all of the strips/cables a few times now and nothing.

I think it must be some dust/loose connection/finger oils as I did wear gloves the first time but rushed it the second. Also I have tried draining the battery and disconnecting the battery, but nothing. So I'm thinking of ordering some alcohol to clean the LCD cable parts, IT MUST BE SOMETHING TO DO WITH THISSS???? YEAH??

Any help is MASSIVELY appreciated, I have spent so much time and money and haven't had a phone for 4 weeks now. I've fixed Iphones before and never had any problems so PLEASE. Heads up if you think somethings broken or if cleaning it should do the trick. Thanks guys!! Happy new year to y'all! x