i would recommend disassembling the case and checking for water damage on the board and battery. if there is water damage attempt to replace the part. if not just dry it out, ***DO NOT USE RICE.***
If that does not work you can either send it to samsung for them to investigate or you could possibly buy either a fake case from amazon linked below.. or you could buy a used case in good condition from ebay for your exact color if you want ti to resemble the original.
[link|https://a.co/d/52UwTMD|fake galaxy buds case|new_window=true]
Hope this helped.