Lately there has been a trend going on with computers being checked in. Many of them have the same symptoms, and are unable to turn on when you press the power button. This can be caused by a number of things: power surge, spilled liquid, physical damage, not working top case, dying battery, or something unknown. The ‘unknown’ has been happening lately, as in the computers that come in don’t work…until they get checked in.
South Burlington has been slammed with repairs in the last several weeks, and several of these ‘no power’ machines have had their batteries drain completely, which, in essence, performs an SMC reset. A SMC, or “System Management Controller”, reset will send a reset signal to the controller that manages the power flow through the machine. When the machines were plugged in on the technician’s desk, they automatically powered on, which is normal when all power to a laptop was severed and restored. All diagnostic tests were run on these machines, and they would always pass with flying colors!
The reason why this happens is hard to pinpoint — unfortunately, when the SMC reset occurs, there is nothing wrong for the test to find. This isn’t always the answer that the worried customer is looking for, because without any other information and all our tests passing, there is no way to replicate (let alone diagnose) any problem that the computer had to begin with.
Per our agreement with Apple, in order to be able to replace any part or fix a computer, the problem must be replicated. We are unable to replace any parts that are not showing any issues. We do have a lot of tests that we run on all diagnostics, but intermittent problems and power issues solved by an SMC reset typically don’t register.
To perform an SMC reset on a machine on your own, press and hold the [Shift] + [option] + [control] and the power button. The machine will turn off if on, and or the magsafe light may come on if it was off. Attempt to boot the machine after performing the reset.