Nice! Good work! 😀
After you get it all up and working I'd recap the board, get a good psu and max it out and you good to go.

Cool! 😀

And back to the drawing board again. Made it rest without power for a while. And it won't start yet again. Now i suspect the caps.

EDIT:
Just as I suspected... When power off for a while it does not POST.
When it has had power on for a while, it will begin to POST again.
Must be tired caps.

EDIT-II:
Another issue has revealed itself. Found this one by mistake.
After having powered the board on, without CMOS battery, I inserted a fresh never used battery.
As it turn's out. The board will not post with any battery.
I really do not know if this have any relation to bad caps or this is unfixable.

Updating the BIOS did not solve the issue with the system not booting with a battery attached.
I had an idea, that the BIOS was curropt in some way, resulting in not booting with battery on it.
Do any know what I should look for now?

Ran the QA-Plus/Pro testsuite that IBM had released for their machines originally.
It passed everything, so it is not the IC's that have any defect.
I have measured the diode, just in casse, that are resided at the battery holder and it's good.
Basically... I can only see that it is the BIOS chip that are defect or the Caps that are "tired".

Replace the caps. 😀

Will do it then. It might even solve the issue with the onboard VGA not working.
The GPU is getting hot, so it is recieving some current.
The testsuite did however not test the onboard gfx, as it is disabled in order to use an ISA vga card.

Any idea on wich caps to start with and wich to avoid before recapping them all?

> It passed everything, so it is not the IC's that have any defect.

I seriously doubt that any tool exists for end users that can test 100%...
The mainboard might not like that you are powering it on from external - it has its own power switch and PS-ON cirquit. Did you give it the 5Vsb at least?

Should I test it with the original PSU again?
You know... To test the power switch.
Or am I missing something?

More progress, or rather the lack of progress.
I did a complete recap of the motherboard, as well as the caps on the riser-card.
Everything is working as they were, before I replaced the caps.
So I guess that the recapping in its self, were a success.
The bad news, is that the issue were not related to the caps.
Oh well.... The board got some fresh cap's. 🤣

The board will still not post with the coincell BIOS battery in place.
Only when the battery is removed, and some time passes, the board will post.
It is as if something does not discharge or something like that, and prevents
something from doing a POST on the board.

I think the issue is in one one the components in this picture.
Does someone recognice this issue? And guide me on to what to measure with
my multimeter...

EDIT...
I have checked the diode (just in case) and it is functioning as it should.

maybe start doing some continuity tests on the power rails and ground rails.

Arhhh.... Shit... Way above my league. I am a bit noob on this, so I am doing this as far as my logic goes.
Not to say that I do not understand electronics, I just don't have any extensive knowledge or education. 😢

That yellow component! Is that a capacitor? And could that be the culprit?
It is linked to the diode somehow and the diode is linked to the battery holder.

I think that looks like a self resetting PTC fuse

True.... Googled it. If it is broken, what impact could it have?

its a fuse, if its broken, nothing shall pass!

PTC fuse by design 're-close' after being blown. they reset themselves. does not mean it could not be broken.

if you have a multimeter you can put it on continuity and touch each side of it with both leads and if it beeps, its not broken.

Think it is broken. Nothing flows. It does not even have any resistans.

Checkes it again today. True enough, no voltage is flowing through that little sucker. That being with the computer turned on. what I can't get my head around, is if this has some impact on the battery issue. I might be wrong on it all together. I simply can not find any info online. As far as I can read the component, it is a 30volt 1.35amp right?

I think that I will give up on this motherboard, I will dump the whole thing, only keeping the CPU and Mem.
It was fun though, recapping the motherboard and all that. Sadly it is beyond my skill's to fix it. 😢

Perhaps I should keep the case too.... Will be a cool thing to build something out of.
Perhaps a mame machine, using newer parts. 🤣

Dude just put it up for sale cheap never know someone might need something from it or might be able to fix it....