Hi @jsass83255
Sounds more like a loose connection either the display flex cable, the daughter board flex cable (some components on this board are used for the display function) or in the LCD display itself rather than on the systemboard.
Here's a [https://www.youtube.com/watch?v=tJV9EbEVriw|video] that shows how to replace the LCD display in the phone which may help as it shows the LCD display cable connection and also the daughterboard flex cable connection (charge port board seen at 1:43 minutes into the video) which you can check first.
If you determine that the problem is in the display, search online for ''Galaxy A12 lcd display'', to find suppliers that suit you best.