That is actually a fake Joy-con, because the battery connecter on a real Joy-Con looked like this:[br]
[image|3562048]
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(image from ifixit guide on replacing Joy-Con batteries)[br]
I've actually bought those fake Joy-Cons before. The motherboard was fake, the casing was crappy, and a lot of functions are missing, like IR and NFC. I would not recommend you to fix this, since there's no point(even the vibrator is from a cell phone and covered by black foam!) Instead, you could buy secondhand ones or just get a new set from Nintendo. Be sure to check whether it's real before you buy it!