ExpressLRS 3.x Flashing Guide: WiFi, UART, and EdgeTX Passthrough Methods — 2026

Your ELRS receiver shows a slow-blinking LED and won’t connect. The binding phrase is correct but the firmware version on the receiver doesn’t match the transmitter module. You need to flash — and ELRS 3.x gives you four ways to do it, two of which don’t require a USB cable. Here’s every method ranked from easiest to “break out the FTDI adapter.”

Before You Flash: Identify Your Hardware Target

ExpressLRS 3.x uses a unified firmware system. Every device — receiver, TX module, or AIO — has a specific target name. Guessing the target produces a brick that won’t boot. The ELRS Configurator (https://config.expresslrs.org) is the official web-based tool. Open it, select your device category, and note the exact target string.

Common targets in 2026:
– Happymodel EP1/EP2: HappyModel EP 2400 RX
– Radiomaster RP1/RP2/RP3: RadioMaster RP1/2/3 2400 RX
– BetaFPV SuperD: BetaFPV 2400 RX
– Radiomaster Ranger (micro/nano): RadioMaster Ranger 2400 TX
– Happymodel ES24TX: HappyModel ES24TX 2400 TX
– NamimnoRC Flash: NamimnoRC Flash 2400 TX

Method 1: WiFi Flashing (Easiest — Receivers Only)

ELRS receivers with WiFi-capable chips (ESP8285, ESP32) broadcast a WiFi access point when powered on without a TX connection.

1. Power the receiver via 5V (not USB — use a flight controller or bench supply).
2. Wait 60 seconds. The LED changes from fast-flash to slow-flash — the receiver is now in AP mode.
3. On your phone or laptop, connect to the WiFi network named ExpressLRS RX (password: expresslrs).
4. Open a browser, navigate to http://10.0.0.1.
5. On the web page, click “Choose File” and select the firmware .bin file you downloaded from the ELRS Configurator.
6. Click “Update.” The receiver reboots after 15-20 seconds with the new firmware.

Troubleshooting: If the AP doesn’t appear, power-cycle the receiver and wait exactly 60 seconds. If it still doesn’t appear, the receiver likely has older firmware (<2.0) without WiFi support — use Method 2 instead.

Method 2: EdgeTX/OpenTX Passthrough (TX Module)

Most ELRS transmitter modules can be flashed through the radio’s USB port without removing the module.

1. Connect your radio (Radiomaster TX16S, Boxer, Zorro, Jumper T-Pro, etc.) to your computer via USB.
2. On the radio, select “USB Storage” mode — not “USB Serial.”
3. Copy the TX module firmware .bin file to the SD card’s /FIRMWARE folder.
4. Eject the USB, navigate to the radio’s System menu → SD Card → FIRMWARE.
5. Long-press the firmware file and select “Flash External ELRS.”
6. The radio reboots the module into bootloader mode and flashes it. Takes 30-45 seconds.

For receivers connected via UART: In the ELRS Configurator, select “Passthrough” as the flash method instead of “WiFi.” Connect the flight controller to your computer via USB. The configurator reboots the receiver into bootloader mode through the FC’s UART and flashes directly. This is the most reliable method when WiFi fails — it uses the UART RX/TX lines we configure in the ELRS binding guide.

Method 3: USB Direct (TX Modules with USB Port)

Modules like the Radiomaster Ranger Micro and Happymodel ES24TX Pro have a built-in USB-C port. Connect directly to your computer. The ELRS Configurator detects the COM port, and you flash with one click. No radio involved.

Method 4: FTDI/UART Recovery (Last Resort — Bricked Devices)

If WiFi fails and Passthrough can’t reach the receiver (bootloader corrupted), you need an FTDI adapter:

1. Connect FTDI TX → Receiver RX, FTDI RX → Receiver TX, FTDI GND → Receiver GND. Do NOT connect FTDI 5V/VCC if the receiver is powered separately.
2. Hold the boot button on the receiver while powering it on.
3. In the ELRS Configurator, select “FTDI” as the flash method and the correct COM port.
4. Flash the recovery firmware (labeled _bootloader.bin or similar).

This method has unbricked every receiver I’ve killed over 3 years of flashing. The only permanently dead receiver I’ve seen was one where a builder shorted 5V to the TX pin — the MCU literally melted.

ELRS 3.x Key Versions

Stick with the latest stable release (3.3 as of mid-2026) unless you need a specific feature from the 3.4 beta. Beta firmware occasionally breaks binding phrase compatibility with older receivers — always flash TX and RX to the same version.

Common Flashing Mistakes

Mistake 1: Selecting the wrong device target. “Radiomaster Ranger 2400 TX” is different from “Radiomaster Ranger 900 TX.” Flashing the wrong firmware produces a device that powers on but never enters bind mode. The only fix is FTDI recovery.

Mistake 2: Flashing a receiver through the FC while the FC is powered by battery. Some flight controllers back-power through the USB port and partially power the receiver, causing the flash to fail mid-transfer. Always disconnect the battery before flashing via USB passthrough.

Mistake 3: Using the ELRS Configurator on a slow internet connection without downloading the firmware manually. The web-based configurator builds firmware on your machine using your browser, but the target definitions update from the cloud. On a slow connection, the build may time out. Download the firmware .bin file while connected to fast internet, then flash offline.

Mistake 4: Forgetting to re-set the binding phrase after flashing. A full flash (not an OTA update) erases the binding phrase. After flashing, power-cycle the receiver, connect to its WiFi AP, and re-enter the binding phrase in the web interface. Without it, the receiver won’t connect to your TX — the same principle that makes ELRS telemetry setup fail silently after firmware changes.

Regulatory Compliance Notice

⚠️ Regulatory Notice: ExpressLRS firmware determines the RF output power, frequency band, and packet rate of your control link. Flashing firmware that enables power levels beyond your regional limit violates telecommunications regulations. In the EU, 2.4GHz is limited to 100mW EIRP; 868MHz to 25mW ERP. In the US, 915MHz operation above FCC Part 15 limits requires a HAM license. The ELRS Configurator does not enforce regional power limits — compliance is the operator’s responsibility. The 2026 ETSI EN 300 328 update in Europe introduces new adaptive frequency-hopping requirements for 2.4GHz devices; verify your ELRS firmware version includes compliance patches for your region.

For pilots running Radiomaster transmitters, the Ranger Micro 2.4GHz module with an RP3 receiver is the combo I’ve standardized my fleet on — WiFi flashing takes under 2 minutes per receiver and the binding phrase syncs everything without a single button press. Grab one from our radio section with pre-flashed ELRS 3.3 firmware.