Question Qosmsio X500 shuts down

[Qosmiouser]

My Toshiba Qosmio X500 laptop shuts down before booting. After pushing the power button the power button and caps lock button lights up, then turn off right away. Then, without even pushing the power button again those buttons light up and turn off repetitively. At the same time the left fan is gently running, then turns off, then repeats this. I had recently changed the motherboard since a computer store told me it is defective. The source for the MBO insists it was checked and working properly before sending it to me. Someone told me perhaps the power cord is defective, though not sure I want to buy another one unless this is the problem....also not easy to find one. Same thing with a replacement video card...not sure if that is the problem. Sounds like a short somewhere, or perhaps one fan doesn't work properly, though I don't know why that would stop the laptop from booting up. Twice recently the fan ran louder for a few seconds, then shut off. One repair person gave the laptop back to me since he could not fix it, and at least didn't charge me. In the meantime I bought another laptop, but still would like to get the X500 working again as a backup, since it was great for many years....before Toshiba threw in the towel on laptops and support.

 

[AlHuneke]

This is not likely caused by a bad power cord. It sounds like the motherboard is bad. I think it's time to but the old horse out to pasture. Was this problem also happening with the original motherboard? If it started to happen with the "new" motherboard, I think you have your answer.

 

[Qosmiouser]

Thanks for your feedback. I am reluctant to send the MBO back to China since the supplier had also sent me a video showing the MBO before. Also I have already changed the MBO more than once, though the last one at least booted up for awhile and then crashed...which was the original problem. Supposedly if the caps lock light goes on (another light rhs top also does) it's supposed to indicate a power issue, though the power and battery LEDs light up, which they did with a similar Toshiba power cord. A small wire connection from left fan is suspect maybe but just guessing. Maybe worth trying to use voltmeter a few places live?