Welcome as well, forgot to mention that in my last post!
Well, I am just recommending a recap right now as it is working, but that's a pretty strong recommendation. The photo is a bit low resolution so I can't tell for sure, but I think I can spot cap leakage/corrosion on the two silver cans on the left, and on the plastic-cased one in the upper right. In any case, it's just about a given at this point that those are gonna need to be changed out. It may work right now, but it probably won't stay working for long with the original capacitors fitted. The ones I see are the three I mentioned, then the brown one and the green one near the big cluster on the left side. The purple cased ones are polymer capacitors rather than electrolytics and typically don't need to be replaced. At this point in 2023, the surface mount and plastic cased caps are always bad in a system of this age, and the corrosion from them will cause board damage and instability. This isn't related to your current boot issue (and sorry that was unclear in my first post), but it will become an issue if not addressed.
And yes, I do believe this one does need a setup diskette.
The object in the top right is the battery from the looks - I saw one similar to that in a rusted out Dauphin laptop I got a few months back. Mine was a different brand than yours, but for me that was a 3.6V Lithium. I'll bet that one's similar, it should have markings on it.