Sadly this story doesn't have a happy ending :(
It started with 1 green line around March 2017 (this question was posted in July 2017). I used to be able to make it disappear by lightly pressing on it, but it would start to come back, and eventually there were two to four.
Through applying the pressure in this manner, over the course of those four months, it escalated into the picture that was attached in the original post. At some point there were only a few lines, and applying pressure would only make them temporarily go away. By the time it got to the state in the attached image, however, pressing the lines only made them turn white or pink, and not disappear at all.
I missed the video link (it's now removed) but I did try taking the phone apart (I don't recommend it!). The back of the phone kind of "peels" off, and the act of taking it off distorts it such that the back of the phone doesn't feel comfortable when it's reattached.