Not sure if anybody will read this but what does the speaker have to do with the bear powering on?

My issue with my iphone 6s started to lag and cant even use it when it gets below 50% health. This started after the 11.3.1 update and has never done this before even after i changed the battery with a unbranded generic battery. Which i had ran a battery test on it and its only at 19% wear.