Reset the SMC and NVRAM first.

Or just close the lid for ten seconds. That fixes it half the time.

The “why” is usually a power management hiccup. When your MacBook Air goes to sleep, it saves the current state to RAM and drops power to most components. Sometimes the firmware gets confused on wakeup — the screen stays black, the keyboard doesn’t respond, and you’re staring at a brick for ten seconds. It’s not hardware failure.

Here’s what I’d do in order:

1. Close the lid, wait 10 seconds, open it. That often kick-starts the wake sequence.
2. If that fails, hold the power button for 10 seconds to force a shutdown, then boot normally.
3. If it keeps happening, reset the SMC (System Management Controller) — on Intel MacBook Airs, that’s shift+control+option+power for a few seconds. For M-series models, just