Hi @rachelcruz
Here's the [https://www.manualslib.com/manual/2895313/Samsung-Sm-T515.html?page=1#manual|service manual] for the tablet that may help.
Go to p.79 and follow the ''Display troubleshooting'' flowchart and check if that shows where the problem is.
There's a board layout on p.69 showing the location of all the components. You may have to zoom in to find the component ID of the components mentioned in the flowchart.
If you find a faulty component search through the parts list (starts on p.35) for the component's ID to find the Samsung part number for the part. Search online for the part number to find suppliers that suit you best.