Hi, yes these are a pain to fix. Hint: if you purchase "DOA" panels to save the AMOLED do a quick test with a UV lamp first. This way you don't waste time trying a panel that is cracked internally.
It does not pick up ones with bad interconnects but if water has got in you'll see patches where fluorescence is absent compared with the rest.
This also picks up units where someone screwed up and tried to cut their losses selling panels on with heat damage, in this case you'll see a circular patch or two where fluorescence is far weaker.
Great for finding hidden screen burn as well.