I had this on my Galaxy Tab S3. Progressively got worse until I had nothing shown on screen at all.
The fix for me was open the back, and clean the corrosion off the wide display cable terminals.
VERY GENTLY scraped it off with a small flat head screw then rubbed with some windex. Put it back together and now it work perfectly
Be very careful cleaning the terminals, the contacts are very thin and it would be very easy to scrape the copper off
Before clean
[image|2320832]
After clean
[image|2320819]