Had the same flickering nightmare with an old galaxy tab. What finally fixed it was carefully cleaning the actual connector pins on the board (not just the cable) with a tiny bit of isopropyl alcohol on a q-tip. A tiny bit of corrosion or dust in there can cause havoc. Reseated the cable a bunch after that, and somehow the third try it just decided to work, go figure.

Read an article about this, and @brian_hart24 it really made me wonder.