According to Award v6 BIOS; 05 means "Blank out screen; Clear CMOS error flag"... meaning to reset the CMOS or change the jumper from "clear CMOS" to "normal". Is this jumper in the correct position?

Otherwise capacitors are almost as likely to fail as the battery and may need replacing.

Although you posted this a month ago, I hope I can help 😀

I've finally got hold of a Toshiba Satellite Pro 480CDT with the same fault - it powers on but it does not power "up". No beeps, no powering up the hard drive and essentially dead. It's a very common fault with the Satellite 220 / 230 and Satellite Pro 440 to 480 models. My code reader showed 0000101 and that's all it would show - that's decimal / hex 05h which is what you're also seeing.
The 490CDT is also troubled by similar faults but it's a different fault type and board design, it's not something I've been able to resolve so I won't cover it here.

Essentially the RTC and Standby battery connectors sit on top of a bunch of data connections that I suspect are RAM related. I too had error code 5 which means SM-RAM - my code reader is just a bunch of LEDs hooked to the parallel port like the maintenance manual for the Satellite 420 describes:

That's also where I'm getting the code from, I don't think they would have changed the code between the 420 series and the 440->480 models.

For reference, here are pictures of the top and bottom side of a Satellite Pro 480CDT in much better condition:

Underneath the two battery connectors, there are a collection of resistors with "220" labelled on them so 22 ohms per resistor and a fairly wide bus, so I think it's RAM signals. It's not like we have schematics or a full toshiba maintenance manual so guessing is the best option for me.

The underside of my broken 480CDT looked like this though, the batteries had leaked *through* the PCB and started working on the traces on the underside of the board:

To continue - I think this problem affects all these models:

• Toshiba Satellite Pro 440CDT / 440CDX / 445CDT / 445CDX
• Toshiba Satellite Pro 460CDT / 460CDX / 465CDT / 465CDX
• Toshiba Satellite Pro 470CDT
• Toshiba Satellite Pro 480CDT
• Toshiba Satellite 220CS / 220CDS
• Toshiba Satellite 230CX / 230CDX

My very sick 480CDT had corroded one trace with a test pad - this is because the greater surface area means more corrosion potential in that space. Most of the other traces are okay. There's no silk screen to see what resistor it is or what trace so I'll demonstrate which one with the pre-repair state:

Then the repaired state - this was after a 2nd attempt where I figured out that soldering to a clean space not between the two adjacent resistors was much easier. The traces I'm using to repair with are single copper strands taken out of an AC power cable because there's no enamel to deal with and they're close to the size of the original traces:

I recommend not using motorised tools to clear the solder mask or clean up traces since I went through a couple of traces with my little engraver tool. A ceramic tool scraper is imo better since they can scrape off solder mask but the traces will usually survive.
The vias were fine but some of the traces - particularly that one trace that has a test pad - had burned / corroded out and I had to repair them but once it was repaired, the system could POST successfully. Then I found out the screen is broken 🤣

If you don't have a fair bit of soldering experience then I recommend taking it to a phone shop for the soldering, the scale of these traces is probably pleasantly big compared to modern devices. But I did get this done without busting out the microscope so it's possible to do.