Left speaker not working

@tonymak time to open both sides and check the wiring to the side that is not working. Make sure that the speaker wires are still connected. After that check the wire coming from the other side. Check that for continuity and check the solder joints. Make sure the the "springs" from the transducer make contact. To work on it and since iFixit does not yet have a guide for it, use something like this video and this guide Sustitución de la Batería de los JBL Tune 600btnc to at least get into it.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!