When doing a screen replacement there is a couple of things to be aware of.
- If the screen is just solid black or green or blue, the mocha tracker will not be able to get a good result on this if you just draw the shape inside the screen. In this case you need to also include some additional detail like the frame of the device inside the track shape
- If the screen has reflections on it you may need to draw a shape which excludes the reflections.
Please see this tutorial video for tips on screen replacements with TrackX: