T61 only boots if power completely removed between boots

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I have a T61 that only boots if power is completely removed between boots. Looking for ideas on whether or not this is fixable, and how to fix it. As I typed this up I wonder if a shorted power button moment switch would cause this?

Symptoms

1. apply power and machine starts booting immediately
2. Boot, forced into CMOS to set date time, F10 save/exit -> boot
   • works like an old laptop
   • relatively responsive
   • All lights and functions I've tested work.
3. Shutdown then attempt to restart with power connected nothing happens
   • does not respond to power button
   • only plug-in power light is on
   • no boot, no action
4. if you disconnect CMOS battery (or just use have a dead CMOS battery), remove battery, disconnect power cable then reapply power cable it will boot again see step 1
5. idles at around 54 C according to psensor but likely just needs the thermal paste refreshed
6. problem is OS independent

What it is:

• Lenovo Thinkpad T61
• type 6465-CTO T7500 Curoe 2 Duo CPU
• BIOS 2.30 dated 2012.02.27

History

• belonged to a family member
• got around 2020 with what thought was dead CMOS battery, tried to fix problem by changing out CMOS battery
• figured out it would only boot if all power removed
• have used intermittently since as described but would like to either make more user friendly now

[RealBlackStuff]

Try this:
Disconnect battery+charger.
Remove the palmrest and then the keyboard.
Plug in the charger.
If nothing happens, you have a faulty Power switch in the keyboard.
Mess around with it to try and get it "fixed".
If unsuccessful, you could either use a USB keyboard.
Or replace the faulty one, all R60/R61/T60/T61 keyboards are interchangeable.
T400/T500 work as well but are a little flimsier.

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That seems rational. Honestly until I wrote out the post and tried to describe the problem logically it hadn't occurred to me the problem was the switch. Then I dug around some more after I posted I found this youtube video https://www.youtube.com/watch?v=sdb41qVk6vg. I might also give it a try.

I won't have time to take it apart until likely next week. Will report back.

Is there a "trusted" source for new or legit new old stock keyboards?

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With the battery out, CMOS battery disconnected, and keyboard disconnected the laptop boots to bios when power adapter is connected.

I did not connect a USB keyboard to get past the bios but I assume that it works just fine.

Presumably this means the switch "short" is on the motherboard or in the inverter. Any thoughts? I suspect it is just easier to keep using it as a "desktop" machine.

[RealBlackStuff]

Wrong, the error/fault is in the power-switch on the keyboard.
Either fix the switch if you can, or get another keyboard.

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I got distracted on other things and forgot to come back to this.

I don't understand why you say it is the keyboard power-switch. It seems to have the same behavior with keyboard in or out, re "keyboard disconnected the laptop boots to bios when power adapter is connected." Wouldn't the switch be a moment switch to connect power to a relay to trigger a power on sequence when the switch is pushed in to connect? If the keyboard is not there, the switch is not there pre-shorted to start boot, but the system still boots. Designing the switch default to open an existing short seems a weird design. What am I missing?

[RealBlackStuff]

Newer models than T61 (e.g. T420) have a Config-option in BIOS to "power on when AC is attached".
T61 also does that (without such a BIOS option).