aminga 500 green screen please help

[hayashi]

(Sorry to butt into somebody else's topic, but once a 500+ battery starts going hairy, is there any way to replace it, or should I just take it out (and how would I best go about doing that?)?

I'm pretty sure there was a bit of fuzz on one side of my A500+'s battery last time I looked, and the beginnings of what looked like verdigris (which seemed to have killed the first 500+ I got, also a green screen) on Gary's socket. Also, the system clock doesn't seem to be working (claiming it's some time in 1991 right now, and the date seems to be the same every day), which would suggest to me that it's dead)

[hayashi]

OK, the battery is off (the pins it was attached to still remain, or, at least, mostly), and the A500+, which was working perfectly before, seems to boot fine.

I'm not too sure about replacing the battery though... neither I or my father know much at all about electronics and soldering (I've only ever used an iron once, and that was years ago and only for a very brief period of time), and I've read that NiCd batteries are banned from sale in the EU for all but specialist purposes now. I read on one article that you can use a NiMH battery... is that true?