Digitizer stops working after a few days

Hello,

I bought 2 screens from the same vendor.

These had a pre-installed front camera and all that stuff, and all I swapped over was the home button.

I installed the first screen, and it ran perfectly for almost a week before the digitizer became buggy and registering touches elsewhere etc.

A few days ago I installed screen #2, and again worked fine for a few days and is now playing up....

Could it be a faulty batch of screens or what could it be?

I installed all connectors fine and installed the metal shield again so I doubt the connectors could have come loose

Thanks