For one sided dead, most likely it's not dead. It's totally battery flat due to contact did not touch the charging pins.
What i previously done is to take out both earbuds, place the dead earbud in for 10 secs(make sure charging case got battery), take it out again and do this process for around 20x or more . This method is to tickle charge the dead earbud back to life. Then u will start to see the dead earbud come back to life with red charging indicator light. I managed to save 2 sets of my earbuds this way, one of it is the samsung buds+. Maybe next time when u encountered dead one side, u can try this method and see if its help.