Breathe. Your Mac is fine.

Second Wind only ever touches the disk where files are stored — never the sealed part of the Mac that makes it turn on. That part cannot be erased, which is why, whatever screen you're looking at right now, one of these three paths brings your Mac back.

1️⃣

Installation was interrupted?

Power cut, battery died, it froze — no problem, nothing was damaged. Plug the power cable in, put the USB stick back, turn the Mac on holding the Option (⌥) key, pick the yellow EFI Boot disk, and let the installation run again from the start. It takes the same 30 minutes as before.

2️⃣

Question mark or blank screen at power-on?

A folder with a “?” just means “no system found on the disk” — the Mac itself is healthy. Use path 1 to retry the installation, or path 3 to return to macOS. Nothing is broken.

3️⃣

Want macOS back?

Turn the Mac off. Turn it on holding ⌘ + Option (⌥) + R until you see a spinning globe. Connect to Wi-Fi and wait: this is Apple Internet Recovery — it comes built into every Mac from the factory and downloads macOS straight from Apple, even with a completely empty disk. Then restore your files from your backup.

💬 Still stuck? Write to us from any other device: get help here. Include a photo of the screen — we answer with concrete steps, not blame.