TP 600X special power-on

[Fusion]

I have a 600X that has this weird problem.
To start it up, I have to press on the IBM Thinkpad logo that's right above the keyboard and then use the power button. Sometimes it works, sometimes it doesn't.
I used to tell poeple that it has a fingerprint reader
I've had it taken apart a few times, never found anything so I used the notebook as an mp3 jukebox for parties.
Any idea where the problem could be?

[rkawakami]

The Sub Card is located just under the IBM logo. It connects the LCD and keyboard to the motherboard. It also contains the lid switch, which if it's broken shouldn't prevent the laptop from turning on. Under that area, mounted to the motherboard, is the DC jack input from the AC adapter. There could be a broken connection in any one of those areas (DC jack, motherboard, Sub Card).

Does the laptop power on correctly with just the battery (no AC adapter)? Once on, does the 600X remain on? Even if you press in that same area?

[Fusion]

Thanks for your reply rkawakami.

I don't have a battery since it died a few years back and then I lost it.
Yes, it does stay on after pressing for about 10 seconds. No problems at all after that.
Sometimes it powers on without pressing. Usually I get a long beep short beep though. (haven't checked the error tables)

[rkawakami]

One long and one short beep error code is not documented in the 600X Hardware Maintenance Manual (as far as I can tell). My guess is that there is a (slightly) broken connection on the motherboard which prevents the normal power-up sequence from taking place. My understanding from looking at the 600X motherboard components is that there are power controller ICs which initially check for proper voltages when the laptop is turned on. If any of the voltages are not present or at an incorrect level, the system will not power up. Since it appears that once your laptop is fully turned on, and it remains on once you perform your "magic", this, to me, would point to the power sequencing circuit on the motherboard.

If you move the laptop, jiggle the power plug or press on the laptop and it still remains powered up, then in my opinion that points to something on the motherboard.