Question about B&O Beolit 17

My Beolit 17 is "broken" after almost 3 years. The problem is that it no longer wants to charge - as if the battery had gone from "ok" status to totally dead from one day to the next. I have seen many reviews on Amazon with similar problems. The device is easy to open and is very well constructed, super quality. Inside a 2200ma battery, unbranded.... very undersized. It could also be the small USB-C port/board, but it looks good (no dirt, not worn out). Bang&Olufson no longer provides support after 24 months... Do you have any advice? Change the battery?