I had a similar problem - Try re-flashing the Marlin 1.1.5

By the way it! It did not take the first time it took me several times before I could get Marlin 1.1.5 Returned to the board then It was ok Again.
And I then Flashed Marlin 1.1.9BF "bug Fix" as Marlin 1.1.9 has bugs and is not worth the flashing on any 3D Printer.