You posted 3 exactly the same images.
Try scrubbing with some vinegar. Leave the vinegar on the leaked battery-base affected area and let it set for 10-15 minutes than nicely clean it up with water or what ever you prefer.

Oh sorry, had to do it quickly because I'm at work :p The links are fixed now.
Going to try the vinegar tomorrow, saw that tip somewhere else too but thanks!
Now it's now up to identifying this board. Saw some similar 386 boards but none really matches this one.

Owkay, an update but a bad one.
I snipped of the barrel battery and cleaned up any visible remains with vinegar and water.
Let it dry for a night and just tried to assemble it. I just tried to power it up with the only the vga card plugge in but I get no image and 3 beeps.
AMI bios code for this is RAM error (64k base memory error).
Is there a chance I damaged something in the process because it worked before disassembly (with the leaking battery installed) 🙁?

3 beeps might be RAM. Check for corrosion under RAM slots and try with only 4 SIMs in BANK 0.

Even when 486 30 pin boards were still current, you often had to push hard on top of SIMM and wiggle them a bit until they made good contact.

I did another check of the surroundings where the battery was and cleaned it again with vinegar, washed off with some water and rubbed some alcohol afterwards.
Changed the RAM that was in bank 1 to bank 0 and kept 1 empty. This finally made the PC come alive again.
Then I put the other RAM (different brand) in bank 1. It still boots but still only 4mb is visible and if I recall correctly, the first time I turned it on before the removal of the battery, 8mb was showing.
So I removed the ones from bank 1 and 1 SIMM is showing some corrosion or maybe even acid damage so I gave it a good scrub with alcohol.
I will try to install it tomorrow and check.
I think I damaged/scratched the board with the small knife I used to pry the battery loose (on the picture right next to the first RAM slot). I hope that's not the cause of the problem now.
I won't be using this machine a lot but 8mb sounds better than 4 and I hate empty slots and sockets 😀
https://photos.app.goo.gl/YhJBvxc10r7QJ2ff1

Still not finding any info on this board too,which is weird.

Thanks for the help so far Stojke!

I just ordered 4x1MB SIMMS so I hope it's the second memoryset that is broken (or at least one of the SIMM's)
Next thing is installing an external battery.

Would anyone have an idea which MB this is?
Below where the barrel battery was, there are 2 jumpers. One is for Color-Chrome but beneath that, is another one and I don't have a clue what it does.
I read that for an external battery,you need to switch jumpers but this one is far from it so I don't know if it has anything to do with it.
You see it on the second pic in my initial post.

What is the motherboard string on the first screen when you turn it on?

I will connect it tomorrow and check it.

https://photos.app.goo.gl/yuKisQMYs8aonlIz1

So it's Aquarius systems...Never heard of that one 😒

Sorry to dig up an old thread, but I also own this motherboard . Do you still own this system?

I recently picked up a Commodore 486SX-25 case, and have the same board to put into it. What cards did it come with?