How to flash a board into a bootable factory system. This is a user-facing walkthrough; the full production/repair technical detail (per-bit boot-strap, LED timing, step-by-step serial flow) is in the factory flashing notes shipped with the firmware.
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⚠️ Boot-strap (selecting the boot medium) is the most error-prone, highest-impact step. A wrong strap only boots the wrong medium — it won’t damage hardware, but the process will "look like nothing happens". The complete boot-strap definition is per the board’s silkscreen + schematic.
Always power off before changing straps / plugging-unplugging — avoid hot-swapping.
Do not cut power during a write. Writes are CRC-checked (a bad image is never written), but cutting power mid-write can still leave it half-written.
Mind ESD. Some boards have power requirements (e.g. R4-Lite’s BE14 tri-band Wi-Fi needs 12V).
Pick one based on whether your board has an SD slot:
| Method | Boards | When |
|---|---|---|
A : SD card |
R4 / R4-Lite / R4 Pro / R3 (have an SD slot) |
The main flow, preferred |
B : Serial + USB stick |
R3 Mini / OpenWrt One (no SD slot); plus brick-rescue for any board |
No-SD boards, or recovering a fully bricked device from the bottom layer |
Why two: boards with an SD slot carry a bootable installer on the card — insert and power on to auto-flash, no serial needed. No-SD boards can only push the first bootloader into memory via the SoC’s BootROM over serial.
Get the files for your board from the Downloads page:
Method A: *-sdcard.img (the installer image written to the SD card).
Method B: the flashkit bundle shipped with the firmware — the in-memory bootloader, the NAND golden image snand-factory.bin and its checksum file snand-factory.crc, the serial download tool, and step-by-step notes.
⚠️
snand-factory.binandsnand-factory.crcmust come from the same build and be copied together. The .crc verifies the .bin before flashing; a mismatch is never written — this protects against a corrupt image, but it also means a version mismatch will "fail verification forever and never write".
On SD-slot boards the product runs on eMMC; since SD and eMMC share one controller, NAND is used as a relay. The flow is boot from SD → write NAND → boot from NAND → write eMMC → boot from eMMC → into the system. No hop enters the OS — power off and re-strap when you see the completion prompt.
Make the card: write *-sdcard.img to an SD card (Etcher / dd, etc.).
Hop 1: strap to SD boot → insert card, power on → writes NAND; power off when done.
Hop 2: strap to NAND boot → power on → auto-installs to eMMC; power off when done.
Hop 3: strap to eMMC boot → power on → into the system (slot A). The SD card can be removed.
💡 Key tip: each hop "boots from A, writes to B", so BOTH straps must be right. Hop 1: besides strapping SD boot, the NAND strap must also be correct; Hop 2: besides strapping NAND boot, the eMMC pin must also be correct. Otherwise it "looks like nothing happens".
💡 Completion is judged by serial output; attaching a serial line (115200 8N1) shows each hop’s write progress and completion. Some boards also have an LED aid (lit while writing, off when done).
Per-board strap bits, LED states, and special notes (e.g. R4-Lite’s NOR/NAND switch, BE14 needing 12V) are in the factory flashing notes shipped with the firmware.
For R3 Mini / OpenWrt One, and brick-rescue on any board. Rough flow:
Per the flashkit notes, use the serial download tool to push the in-memory bootloader into the device’s RAM (no flash write).
Copy snand-factory.bin + snand-factory.crc to the root of a FAT32 USB stick, plug it into the device’s USB port.
The device auto-detects the stick and writes NAND (CRC-checked before writing, read-back verified after).
R3 Mini needs one more step: remove the stick, strap to NAND boot, and it auto-installs the system to eMMC; OpenWrt One is NAND-only, so a single write is enough.
Step-by-step commands, wiring (UART0 / Type-C), and LED states are in the serial-flashing notes shipped with the firmware (the flashkit bundle includes a per-board step-by-step guide).
After entering the system:
Open https://192.168.100.1 in a browser — the setup wizard should appear → continue to [First-time Setup].
If a serial line is attached, you can confirm both firmware slots boot (A/B dual slot ready).
You’re ready to use it. If something goes wrong, see [Recovery and Rescue]。
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