What does the ThinkPad "power button trick" do?

Question

While searching for a fix for my broken ThinkVantage Power Manager, I came across a forum post suggesting that I press the power button ten times after disconnecting power to the machine. At first I thought it was a joke or a troll, but there are other reports suggesting the same thing — or very similar variations, at least — as a solution for a variety of problems.

Even though this technique seems to be successful in some cases, I couldn't find the reason that it works. Most posts either jokingly refer to it as a magic fix or avoid the "why" aspect entirely. I do remember one vague reference to it influencing the BIOS, though I can't find the source again now. So, what does the ThinkPad "press the power button ten times" thing actually do?

Answer 1

This is similar to Dell and HP, but instead you hold the power button in for 15 seconds with the AC and battery power removed, it discharges the motherboard of any residual voltage, sometimes this fixes small bios issues.

For a more complete bios reset, remove AC power, main battery, and then the cmos (RTC) battery, leave the cmos battery out for 15 minutes before re-connecting it. You will need to immediately enter the bios and set the date and time after this procedure.