A client recently brought in his laptop, an Inspiron 1545, which was exhibiting some strange behaviour. The laptop would quite often refuse to start, though the charger was functioning correctly and the battery was in good condition. The power circuit on this model consists of a power button which presses on a switch which is itself connected to the motherboard via a cable ribbon.
The button is mounted on a panel and has two arms on either side which allow it to flex. On the back side of the button is a bit of plastic (circled in blue) which, when pressed, pushes on the switch. The points where the arms connect to the panel (circled in red) are a weak spot and can disconnect, allowing the button to shift about.
In addition, the cable ribbon connector from the switch (circled) to the motherboard is a potential trouble spot.
Using some high-tech super-glue, I re-attached the button arms to the panel which would guarantee a good connection with the switch and then reseated the cable ribbon in its housing. Once it was back together the laptop fired up as it should.