We own total of 3 Dell D610 laptops. These were very popular at some point and now they are cheap and plentiful. If the laptop works it is not a bad machine for email and web browsing. Although running most of the flash games it is out of the question. But this post is not about how good the laptop is but about one common problem. These laptops tend to stop reacting to the power button. User has to press power button harder and harder which in fact makes the problem worse.
The problem is that the power button is mounted on the panel and the panel is plugged in to the female connector on the main board. The female connector is soldered poorly on some models and gets loose from the motherboard. It is held just by solder and nothing else.
To fix the power button one must almost completely disassemble the laptop. I would not get in to the disassemble procedure as it is available online elsewhere. The goal is to expose this connector and effectively to take out the motherboard. The connector must be accessible with the soldering iron from all sides.
You will need two soldering irons, one about 40 to 60 watt with a large tip and one 25 watt with a small tip.
After disassembling the laptop, reheat large pads of the connector with the large iron and small pads with the small iron. Make sure the solder is melted well and connection is restored. The power button will work like new after that. Do not overheat motherboard and the connector otherwise you are risking lifting the cooper trace.