Alright, I've gone through the manual and I believe I've configured it correctly - no boot and no beeps at present. I took a stab at trying a POST card, and I've attached a photo of the code I'm seeing.

This is supposedly an Award BIOS based on the manual.

The (admittedly poor) manual I got with the POST card suggests that this is the point where the BIOS checks for the battery condition. I've made a rather hack jobbed attempt to wire a CR2032 to the External Battery header with no success, but I'm honestly not sure if that's the right thing to try.

I'll also note that I get the same code with or without RAM, and with or without a VGA card. I've yet to try putting any multi-i/o card in.

Does it sound like I might be on the right track here? Any suggestions for what to try next? I'd like to get this board operational, it'd be my first 486 desktop since probably the mid-to-late 90's, and that one I was too young to do much with.

so looking at your external battery connector pin1 should be positive and pin 4 negative (the one closest to the edge of the board) is that how your connecting it?

check your battery with a multimeter to see how much it is putting out could be a bit flat and they only output 3v.

If the external battery is not working then the next easiest step is solder to wires to the normal battery header and attach a working barrel battery if you have one. This will cover any battery boot issue 100% unless the physical traces have damage

I believe that was how I was connecting it - there's a good chance the battery I was using is a bit flat though, I'll have to test.

The rest I may need to wait until pay day - the soldering equipment I have on hand is way too powerful for a circuit board (it's an older Weller gun-style), and I can't find my multimeter. I also don't have any spare working barrel batteries - would a 3xAA pack possibly work?

the internal battery is set to be automatically charging, the barrel is rechargeable but connecting AA pack to internal terminals is not a good idea because they will be sending a voltage back to the AA which are not rechargeable. Don't do it

But why don't you connect the 3xAA to the external battery terminal, external battery header does not charge the battery

Interesting board. Perhaps the predecessor to the MB-8433UUD? Are you able to benchmark it against the 8433UUD?

I'd love to be able to benchmark it, but no luck getting it to post yet - not to mention this is literally my only 486 Desktop motherboard and I only have this DX33 and a SX25 in a Toshiba T1910CS for available 486 processors.

If I get it to post and run then I'll definitely run some benchmarks. Right now I'm waiting for available funds to get a proper multimeter, soldering iron, and 3xAA battery pack to see if that gives me any luck.

I'm also working under the assumption that the fact it's giving me any post codes at all is ultimately a good sign the BIOS is probably OK and the CPU is functional. Not sure if these are safe assumptions or not. As well I'm a bit limited on RAM to test with so I'm really hoping the sticks I have are working.

I don't know. I've never had any great success with POST cards.