Boot from USB
Open the one-time boot menu and choose the UEFI USB entry.
Boot menu, not a settings adventure#
The boot menu is a one-time list of devices the PC can start from. BIOS/UEFI setup changes lasting firmware settings. Try the boot menu first; it is safer and usually all you need.
- 1Shut the PC down completely.
- 2Insert the flashed USB and connect Ethernet, keyboard and monitor.
- 3Turn the PC on and immediately tap the boot key about twice per second.
- 4Choose the entry that starts with UEFI and matches the USB brand or capacity.
- 5Wait for the ZimaOS installer menu.
| Manufacturer | Common one-time boot key |
|---|---|
| Dell | F12 |
| HP | Esc, then F9 |
| Lenovo | F12 |
| ASUS | F8 |
| Acer | F12 |
| MSI | F11 |
| Gigabyte | F12 |
| ASRock | F11 |
| Other | Esc, F8, F9, F10, F11, F12 or Delete |
Keys vary by exact model. Search the manufacturer’s support page using the model number when these do not work.
If the USB is missing#
The menu has no USB entry
Move the stick to a USB 2.0 port if available, try another port, then reflash or try another stick. In UEFI settings, confirm USB boot is enabled. Change only what you can identify.
Secure Boot blocks startup
The current official ZimaOS install guide says Secure Boot must be disabled and UEFI mode enabled. Record the original setting before changing it. Do not disable unrelated security features.
The PC returns to Windows
You probably selected the internal Windows drive or missed the boot key. Shut down and try the one-time menu again. Avoid changing the permanent boot order unless the menu is unavailable.
Black screen or no keyboard
Wait two minutes, try a different video output or wired keyboard, remove unnecessary USB devices, and retry. Older PCs may initialize USB 2.0 more reliably than USB 3.0 during boot.