Make sure the battery is charged - Mac notebooks can run out of battery, and in these cases, the computer will go into a deep sleep power mode and won't turn back on until it's been charged a little. Try leaving the computer plugged in for a while, and then try to turn it on again.
The power button is behind the computer on the left side as you face it. Next, press the power button. Wait a minute or two. Try using the F2 key to increase the brightness of the screen in case that's turned down.
The devices this article applies to include the MacBook Pro, MacBook Air, MacBook, iMac and the Mac Pro. In case the Mac becomes inaccessible as a result of whatever the issue causing the white screen, make sure you keep a backup of whatever information you have been working on saved.
It may also include the Apple logo, a spinning gear, a spinning globe, or a prohibitory sign (a circle with a slash drawn through it). In all cases, your Mac seems to be stuck. There are no unusual noises, such as disk access, optical drive spin up or down, or excessive fan noise; just a Mac that won't continue to the login screen or the desktop.
Is power supply out? After a couple of power bumps to our home's system, and power was restored, all home electrical panel breakers were still in the on or untripped position. The 6 outlet power strip, my iMac was plugged into, was still on, again, untripped, but my iMac will not turn on.
Apple MacBook might have low market share compared to PCs. But they are still preferred by tech enthusiasts, designers, and CAD artists. However, it doesn't mean that they don't run into the occasional trouble. The OS might crash, and your MacBook Air won't turn on. In such an instance you can try the following to fix your Mac.