^ we live in very wasteful society. Almost everything is made to be as unrepairable as possible. Tv,fridge,phones you name it.
My headphones wire ripped off and I went to many shops for soddering. Buggers didn't want to repair it for just 20rs. I even offered 50. Got fed up, ordered sodering iron on amazon and repaired it myself with no prior experience.
I assume its the same case with your chromecast. No one wants to do opening,sodering and closing it for sake of 50rs. You'll be better off buying a new chromecase since shipping will add extra money into equation