Short version: you need the right firmware file and your radio in DFU (bootloader) mode. Get both right and the actual flash takes about two minutes. Here's the whole process, plus the button-mashing part that trips people up.
This covers our RM-1 and RM-2 radios specifically, along with general steps that apply to most other Meshtastic hardware — Heltec, RAK, T-Echo, all of it. The exact way you trigger DFU mode is the one thing that's genuinely different from radio to radio. We'll call that out where it matters.
Step 1: Get the Firmware File
You've got two sources, depending on what you're running.
Option A — meshtastic.org (any Meshtastic device)
This is the source of truth for stock Meshtastic firmware, and it works for any supported board.
- Go to meshtastic.org/downloads and find the firmware release for your exact device
- Or use the Meshtastic Web Flasher — it downloads and flashes in one step, right from Chrome or Edge (Firefox and Safari don't support the WebSerial/WebUSB it relies on)
Option B — firmware.at-labs.tech (RM-2 only)
If you're running an RM-2, use firmware.at-labs.tech instead of stock Meshtastic. Pick the variant you want to run and download it. This is RM-2 specific — the RM-1 runs stock Meshtastic (or Reticulum/MeshCore) with no custom firmware of its own, so RM-1 owners should use Option A above.
Why this matters: AT Labs firmware pre-configures transmit power safely for the RM-2's radio module. Stock Seeed XIAO firmware will let you set TX power up to 30 dB in the app — on the RM-2 hardware, that will permanently damage the radio. The AT Labs build hard-clamps this so it can't happen by accident. If you flash stock firmware anyway, manually confirm TX Power is set to ≤ 8 before you transmit.
Step 2: Put Your Radio Into DFU Mode
This is the step that's actually different across devices. Find your radio below.
RM-1 / RM-2: Double-press the reset button on the bottom of the unit. A new drive will mount on your computer — that's DFU mode confirmed.
Other nRF52 boards (RAK4631, T-Echo, etc.): Same as the RM-1/RM-2 — double-press the reset button.
RP2040-based boards: Hold the BOOTSEL button, and while holding it, plug in the USB cable. Release once the drive mounts.
ESP32 boards (Heltec, T-Beam, Station G2, most others): No button dance needed. Just connect via USB — the Web Flasher talks to the bootloader over serial automatically.
Step 3: Flash It
If a drive mounted (nRF52 / RP2040 devices, including RM-1 and RM-2):
- Open the mounted drive — you'll see
CURRENT.UF2,INDEX.HTM, andINFO_UF2.TXT - Drag the
.uf2firmware file you downloaded in Step 1 onto that drive - Once the copy finishes, the radio reboots on its own and installs the new firmware
If you're using the Web Flasher (ESP32, or nRF52/RP2040 if you'd rather skip the manual drag-and-drop):
- Go to flasher.meshtastic.org in Chrome or Edge
- Connect your device via USB
- Select your exact device model and the firmware version
- Choose a normal flash to keep your existing settings, or "Full Erase and Install" if you're jumping several versions or the radio's been acting up
- Let it run — it'll tell you when it's done
Most common failure: a charge-only USB cable. If the flasher can't see your device at all, that's the first thing to check.
Step 4: After the Flash
Once the radio reboots, reconnect in the Meshtastic app and confirm your node comes back up with the right region and channel settings.
RM-2 owners — check this every time: After any firmware update or factory reset, confirm TX Power is set to ≤ 8 before you set your region or key up. This is the one setting that can damage the radio module if it's wrong, and a reflash is exactly when it can reset to something unsafe.
The Over-the-Air Option (Use With Caution)
Full disclosure: I haven't personally done an OTA firmware update on any of these radios. This section is based on how Meshtastic documents the process, not firsthand experience — so take it as "here's how it's supposed to work," not a personal recommendation.
nRF52 devices can technically accept firmware updates over Bluetooth, no USB cable required, using Nordic's nRF Connect app (Android) or the nRF DFU app (iOS). The catch: Meshtastic's own docs flag this as higher-risk than the wired method — if the update fails partway through, the radio can be left in a non-working state that needs physical access to recover. On the RM-2 specifically, our own guidance is not to attempt a BLE firmware update at all — the aluminum housing attenuates the signal enough that it's prone to failing partway, and a failed OTA update is how you brick a radio.
If you want to try it anyway on a device where it's supported:
- Download the firmware release for your device
- On Android, use nRF Connect App version 4.24.3 specifically — the current release isn't compatible with Meshtastic updates. On iOS, use the nRF Device Firmware Update app from the App Store.
- Connect to your radio in the app, select the DFU option, and choose the firmware file ending in
-ota.zip - Let it run — BLE transfer is slow (1–2 kB/s is normal, not stuck), so don't disconnect early. On iPhone, keep the screen awake so auto-lock doesn't interrupt the transfer.
Our take: the drag-and-drop / web flasher method above takes about the same amount of time, doesn't carry a brick risk, and doesn't require finding an old app version. Use OTA if you genuinely can't get to a computer — otherwise, do it the old-fashioned way.
Wrapping Up
Whole process, start to finish: download the right firmware, get the radio into DFU mode, drag the file over (or let the web flasher do it), double-check TX power if you're on an RM-2, and you're done. The only part worth being careful with is matching the right firmware source to your radio — AT Labs firmware for RM-2, stock Meshtastic for the RM-1 and everything else.
If you're managing more than a handful of radios at once — a team, a unit, a whole kit — this is exactly the kind of thing that gets tedious fast doing one at a time. That's part of what the Response Crate's NodeReach tooling is built to handle. Worth a look if firmware day for your team means more than one or two radios.
Questions on a specific radio not covered here? Reach out — happy to help you track down the right process.
