Got myself an Olivetti M300-10 with 386SX/20 and 12MB memory. BIOS-setup gives error from battery but can't find battery anywhere, looks like it has been removed already. Motherboard has one 4-pin connector that looks like it's for the battery. Tested pins with multimeter and 2&3 are ground ja 1&4 are something else but shorted together. Tried CR2032 on to pins 3&4 but didn't work.

Done lots of googling but can't find anything useful about this. Motherboard is BA289. And no, there's no Dallas or Odin etc. on mobo.