Fixing DFPlayer Mini with no sound

My DFPlayer Mini module arrived from China as it did not produced any sound on the output. I'm getting tired lately with the quality problems of cheep modules, so this time I did not asked for refund, instead was suspecting a soldering problem. And I was right.

I also measured the current draw [1:56], and discovered the speaker polarity [2:25].

Online documentation: https://www.dfrobot.com/wiki/index.php/DFPlayer_Mini_SKU:DFR0299 ... https://www.youtube.com/watch?v=7C_znVEeQYE