Chosen Solution
I replaced the digitizer and battery on my iPhone SE. I’ve done this several times before and I was very careful, as always. However, when switching on the iPhone - half of the screen is black. Touch is working on the black side. I tested two more new digitizers - same problem! My conclusion is that the LCD connector has become broken/defective. BUT I’ve examined it very closely and it looks fine. What could be wrong? Could the new battery be the problem? Please zoom in on attached photos to see problem + LCD connector.
The cheap aftermarket 5s screens will show issues like this on the iPhone SE. Look for a replacement screen that is specifically compatible with the iPhone SE and it should have no problems.
Could be a bad batch of digitizers as well? Damaged during shipping etc. try the digitizer on a different phone just to verify that it functions properly. Otherwise it’s gotta be the connector. Hope this helps.