Recovery

Recovery

NebulaOS has four ways back, from automatic to last resort. Use the first one that fits.

Situation	What to do
A new system image does not come up properly	Nothing: NebulaOS goes back by itself (below)
NebulaOS runs, but you want the other slot	Settings → Reset → Swap boot slot
The screen is dead but the printer is on the network	SSH, then switch the slot (below)
Nothing starts at all	USB recovery from a computer (below)

1. Automatic: the trial start

After a system image install from the screen, the new slot starts as a trial. If Klipper and the screen do not come up within about 5 minutes, or the new system resets before it is confirmed three times (for example the watchdog after a freeze), NebulaOS switches back to the previous slot once, by itself. The screen then says what happened.

Not covered: an install through Creality's updater (that one has no trial), and a kernel that does not start at all.

2. Swap the boot slot on the screen

Settings → Reset → Swap boot slot restarts into the other slot. The confirmation says what is in it. Coming back from a stock or OpenKE slot needs SSH or USB (below), because those systems have no NebulaOS swap button.

Do not power-cycle a printer that runs the stock system: a stock power-on can flash old firmware into the mainboard. Use a soft reboot.

3. Over SSH

Both NebulaOS and stock/OpenKE accept SSH as root. The slot is chosen by a marker; the steps are in NebulaOS-firmware's slot switching guide.

4. USB recovery from a computer

For a printer that does not start. The printer's board has a USB recovery mode (mask ROM): power off, hold both small buttons next to the screen's micro-USB port for 3 seconds, release the reset button first. A computer then talks to the board over a USB cable.

• Switch the boot slot back (Linux, tested 2026-10-14): NebulaOS-firmware's tools/recovery/usb-set-boot-slot.sh A or B, with the pinned usbboot tool. Nothing else is written. Steps: Developer recovery.
• Write a whole system again: each release has a .ingenic file for the Ingenic USB Cloner. It rewrites the printer from scratch: NebulaOS in slot 2, Creality's stock system in slot 1. It erases your settings, prints and calibration; only the printer's factory serial number and network address are kept. Not tested by NebulaOS on a printer yet - use it only when nothing else works.

What survives a slot switch

Your printer.cfg, macros, moonraker.conf, Wi-Fi networks, uploaded files and screen settings live on the shared data partition and stay. The two systems keep their own settings apart.