I pulled all the cards, pulled one floppy (it's a dual floppy with hard drive). The hard drive connects to a SCSI card, not onboard, so it was pulled with the card.

I didn't notice any leaky caps although usually in my experience that manifests it's self as bad/no audio rather than complete failure.

Batteries were installed fine and tested with a meter for 3.6V. I have a basic meter that can test voltage, resistance, etc.

Keyboard is good. Good 120V AC power coming in. Tried a few things like powering on/off and pressing the button, etc. (sometimes makes other Macs work that are kind of flaky).

Motherboard is full of RAM.

I have no other PSU to test with. Maybe I can get a hold of a Mac II/IIx or another IIfx to see if it's the PSU.