89' xj6 alternater problem HELP ME PLZ!!

:crying: i have a 1989 xj6, my battery died and my mate desided 2 try start it 4 me buy putting his battery in then kicking it over and while its running swap them back.. well it worked the 1st time but then the next time we tryed it wouldnt stay running and it wont charge at all and my dash computer is saying i have a curcit fault.. how can i fix this? does anyone no wat i broke?

i would have alt tested because it maybe the regulater also or your battery might have a short in it.

awsome thanx mate.