T430 mainboard damaged?

[kony]

I have had an annoying issue with my T430 for about last two weeks.

When I press the power button to start up the laptop, it boots for about a second (all hardware seems to be powered, the monitor turns on, I can hear the HDD and so on) and suddenly turns off. Then it's off for like 3 seconds and boots itself again, this time working properly. The same issue happens when restarting the laptop (both from Debian and Windows).

- The issue occurs when the laptop is connected to the AC power adapter and has battery in
- With AC power adapter plugged off and battery in, the issue persists
- With AC power adapter in and battery out, the issue persists
- When turning the laptop with fingerprint reader instead of power button, the issue persists, in addition the second boot up shows clearly that the laptop loses the data between the boot ups, because I have to put my finger on the fingerprint again so the security would let me through, which should not be the case when booting up via fingerprint reader
- the issue does not always happen, but it usually does
- with everything plugged out (any USB or other external device, including ultrabay) the issue persists

After some time this issue is driving me mad. It adds some time to the boot time process, I have to scan my finger twice and especially because T series costs premium, so one would expect a decent quality build that doesn't break down after just one year of use. It probably slowly kills all my hardware too, I can't imagine such boot->power cut->boot process to be healthy for HDDs and other devices. I fear it might shorten the life of the devices in the laptop significantly.

Is it certainly mainboard's fault or something else might be at fault? I can't really send it to service, because I absolutely need the laptop right now and will for at least a few months and even two weeks without it would be a huge loss. Is there anything I could try on my own?

EDIT:
I'll add that pressing the power button so the laptop would go into sleep mode (and then out of it) works just fine.

EDIT 2:
Oh, and two more things:
Lenovo diagnostic tools show no issues with any of the hardware.
BIOS version is 2.67 and it was updated quite a while before the issue appeared, so I guess I can rule it out.

[RealBlackStuff]

What happens if you remove the HD and boot from a Linux Life-CD?
Did you update the BIOS recently?

[kony]

BIOS was updated weeks ago and I had no issues until recently.

Disconnecting the drives does not help either, the error happens before even BIOS gets to boot.

[RealBlackStuff]

Remove the palmrest with FPR, then try to boot.
Maybe the FPR is defective?