Your wiring seems okay. But a bit messy. I recommend not splicing so many wires in random spots. And do not leave so much exposed wires. As for hissing. That it pretty normal with pwm audio. You will likely always have some hissing. Also just to confirm. You have the proper text added to the config...

Did anybody figure out the solution for this screen?

This is a very minimal shoulder button bracket made with perfboard, 2 tactile push buttons and 3d printed holders to keep it in place: https://preview.ibb.co/bw06T7/IMG_20180218_113600072.jpg Do you have an stl for your pieces that hold the bracket and a picture of it installed? I have all these ma...