Key battery

Recently I bought some cheap ahh golf 4, has a bit of rust and a few plastics are loose, paint-job not the worst not the best, a 1999 (Car's older than me) ,bought with the thought to commute to work in near future and rn for school, the key is old and I could barely find even a youtube channel that'd dissmantle it but eventually did, it's got only the unlock and open button.

Main problem is it doesn't unlock nor open the doors with a click of the key, so I have to do it manually. When I dissmantle the key, the type of batteries doesn't seem to be written anywhere, but the previous owner put CR1620 3V in them, the sacket is too big for CR2032- which is I think the most popular for mk4 golfs.

I put the CR1620 in every way possible,- none variation worked and the batteries appear to be a bit loose in the sacket, the green thing inside (whatever it's called) is loose, one of the X shaped pillars is literally stuck in one of the holes of the green thing.

So I'm just curious if anyone has had the same or similar problem with the key and if so what was the price range for fixing it, was it hard to fix?