Topic: Right Joy Con not syncing properly

Recently I’ve changed the shell of both my joy cons. The left one was a success but the right wasn’t as successful. The only way the joy con works now is when it’s docked to the console, and even then when I go onto the controller settings to see how charged it is, it shows it’s nearly dead so I swapped batteries to the battery that’s fully charged and even then it’s showing red on the system and nearly dead again. As soon as I undock it there’s no lights on the side to say it’s on, now the sync button isn’t working and when I try to turn the joy con on while undocked, it doesn’t work. Please help!