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I have a IBM ThinkPad T42 that will not turn on. When I press the power button all the lights light up green. About a second latter all turn off except 2, one of which is the battery and the other is the power. The laptop then begins to beep. A few seconds after 3 lights turn off the battery light turns yellow and the power cable is still green. Any suggestions on what my problem is and how I can fix this?

UPDATE: There are no CDs in the tray. There are nothing plugged into USB or anything else (other than the power cable).

I have tried to start without the battery. The power light is green but it still makes the beeping sounds and does not start.

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What's the beep sequence? That would be very helpful diagnosing the problem. Here's a list of Thinkpad beep codes: – Velociraptors Aug 11 '10 at 1:18
It is 4 cycles of 4 short beeps. – Josh Curren Aug 11 '10 at 10:53
up vote 5 down vote accepted

As a former Lenovo tech, I don't even need to look up that code - 4x4 beeps is the TPM on the system board. Unfortunately, on the T42's there is no easy way to reset that...clearing the CMOS /might/ work but I dunno.

There is the slight possibility it's just static - take the battery out of the machine, unplug everything, hold the power button for ~30 seconds, release, tap a few times, hold again, release. Plug the AC adapter back in and leave everything else out - this MAY fix the problem. If it doesn't, you can try opening the machine, pulling out the CMOS battery, and leaving it for an hour. If that doesn't work you're probably looking at a system board replacement.

(I have seen ONE instance where a bad stick of RAM was causing this so it's worth looking into but it's INCREDIBLY unlikely.)

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On most computers a short system self-test runs when it is switched on (usually by the BIOS). If the computer only beeps and turns off again, this usually means the self-test failed (i.e. there is a hardware error). The beeps usually tell you which component failed (motherboard, video card, ...).

See Velociraptors' comment to the question for a list of Thinkpad beep codes. Look up yours and repair your laptop...

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I think its a IBM thinkpad T(64?) one beep-pause-two beeps before before beeps num, cap lock, z symbol and charging are lighing up - no battery is in use after beeps only symbol and charging are lighing up

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Welcome to superuser. Do you have any documentation to back this up? Facts are useful, guesses or "I thinks" are not. – Moses Sep 21 '13 at 3:51

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