RadioMaster Boxer — EdgeTX and internal ELRS firmware upgrade bench guide

Purpose and boundary

This is a bench-only preparation guide for an owned RadioMaster Boxer ELRS transmitter. It covers safely preparing an EdgeTX update and an internal ELRS module update, then collecting evidence for a later controlled link test. It does not authorize receiver binding, RF transmission, flight-controller configuration, motor output, or flight.

Hard stop: do not start if a vehicle is powered with props installed. Keep every aircraft/receiver unpowered and disconnected during the transmitter firmware stages. If a receiver must later be powered for a link test, use the Drone Lab safety boundary: props removed, motors disabled where possible, bench restraint, and an emergency power-off plan.

Before touching firmware

Create an evidence folder and record:

• Boxer exact hardware variant and serial/revision label.
• Existing EdgeTX version, existing internal-ELRS version, and SD-card state.
• Current model export or backup location.
• Computer OS, USB cable identity, and available data ports.
• Intended official source URL, file name, version, checksum or release provenance.
• Rollback file/source for the currently installed version.

Do not choose a generic target because a similarly named radio appears in a video. The official ExpressLRS guide says off-the-shelf hardware should use a hardware-specific Configurator target; if it is absent, stop and contact the hardware manufacturer rather than guessing.

Phase A — Safe bench setup

1. Turn off the Boxer.
2. Keep all aircraft, receivers, and flight controllers unpowered. Do not attach a USB-powered vehicle.
3. Remove props from any nearby bench vehicle and keep its battery disconnected.
4. Use a known data-capable USB cable; charge-only cables are a common false failure.
5. Close any app that can hold a serial/USB port.
6. Photograph or export current model settings before changing firmware.
7. Verify you can identify the normal boot path and the recovery/bootloader path from official Boxer documentation before flashing.

Stop and diagnose if hardware identity, current version, backup, official target, or rollback source is missing.

Phase B — EdgeTX update

B1. Select the exact release

1. Open the official EdgeTX release/update documentation and the official RadioMaster Boxer support/download page.
2. Confirm the firmware target says RadioMaster Boxer, not a similarly named radio.
3. Record the chosen EdgeTX version and the matching SD-card-content version in the evidence record.
4. Download only from the verified official release/vendor path; preserve the downloaded filename and checksum/provenance.

B2. Back up first

1. Back up models/settings using the supported EdgeTX/Companion workflow for the installed release.
2. Copy the existing SD-card contents to a dated backup folder before replacing anything.
3. Do not overwrite the only recovery copy.

B3. Flash and validate EdgeTX

1. Enter the Boxer bootloader/USB path following the verified Boxer instructions.
2. Use the official EdgeTX flashing route for the exact Boxer target.
3. Flash once; do not repeatedly retry an unexplained failure.
4. Power-cycle the radio after the tool reports success.
5. Confirm the expected EdgeTX version on the radio.
6. Confirm normal buttons, gimbals, screen, storage access, and model list work.
7. Replace or align SD-card contents only with the bundle that matches the installed EdgeTX release.
8. Record the successful boot and any SD-card warning exactly as displayed.

Success criterion: the radio boots normally, shows the expected version, does not report an SD mismatch, and the backed-up model list remains available. Leave RF/link features disabled until the separate controlled test.

Phase C — Internal ELRS update

C1. Establish compatibility plan

1. Identify the exact internal ELRS hardware target from current official RadioMaster and ExpressLRS documentation.
2. Pick one supported ExpressLRS major-version plan for the transmitter and the owned receivers that will later be tested.
3. Record the planned target, firmware version, update method, and rollback source.
4. Do not use a configuration copied from an older video merely because it says ELRS 3.x. ExpressLRS documentation currently displays newer releases; confirm support for your exact hardware before selecting a version.

C2. Flash only the verified transmitter target

1. With aircraft/receivers still unpowered, connect the Boxer using the documented data USB port and mode.
2. In the official ExpressLRS Configurator, select the hardware-specific Boxer internal 2.4 GHz target that you independently verified.
3. Confirm the selected target and transport/port one more time before flashing.
4. Flash once through the documented method for that target.
5. Wait for the tool to finish and record the complete success or error text.
6. Reboot the radio and verify the displayed internal-ELRS version using the supported radio/ELRS interface.
7. Install/update the matching ExpressLRS Lua tool only from the official version path and place it in the documented EdgeTX tools location. Confirm it opens without an error.

Do not proceed to binding, packet-rate changes, transmit-power changes, or flight-controller work in this guide. Those are a separate, controlled RF bench-test stage.

Phase D — Firmware-only acceptance record

Mark this guide complete only when all are true:

• EdgeTX target/version and source provenance recorded.
• EdgeTX booted normally after update.
• SD contents match the installed EdgeTX release or no mismatch warning is present.
• Exact Boxer internal ELRS target/version recorded.
• ELRS update completed and version verified on the radio.
• Lua tool loads without a version/script error.
• Models/settings backup exists and rollback source is available.
• No receiver or vehicle was powered, bound, armed, or flown during this procedure.

Troubleshooting method — UI, DFU, USB, or flash errors

The phrase “DUI error” is ambiguous, so this guide treats it as a request for a UI/DFU/USB/flash-error method. Preserve the exact message or a screenshot; do not paraphrase it into a guess.

The six-field error record

Time and step:
Radio state: normal boot / bootloader / USB mode / powered off
Computer OS and flashing tool version:
Exact selected firmware target and version:
Exact port/device shown by the tool:
Exact full error text or screenshot:

Diagnostic ladder

1. Classify the failure before changing anything. Is it discovery, target selection, transfer, verification, boot, SD content, or Lua-script failure?
2. Check the physical layer once. Use a known data cable, a direct port, and no USB hub if possible. Reconnect once; do not loop retries.
3. Check the radio mode. A radio in normal boot, bootloader, USB storage, and serial-VCP mode can enumerate differently. Use only the mode called for by the verified official procedure.
4. Check exclusivity. Close Configurator, Companion, serial monitors, and other software that can retain the port. Re-open only the required tool.
5. Check target identity. Compare the exact hardware target, region/band, and firmware major-version plan against official docs. If there is any mismatch, stop; do not flash a generic or neighboring target.
6. Check source integrity. Re-download only from the official source if checksum/provenance, file size, or release identity is uncertain.
7. Check recovery before retry. If the radio fails to boot or the tool reports verification failure, preserve the error record and use the official recovery/unbricking procedure for the exact target. Do not improvise a bootloader command.
8. Retest one variable at a time. Change cable or port or radio mode or tool version—not several variables together.

Symptom map

Escalation packet

If a failure remains after the ladder, prepare this minimal support packet for the official RadioMaster or ExpressLRS channel:

• hardware photographs showing label/revision;
• exact firmware target/version and source URL;
• flashing-tool version and computer OS;
• complete error log/screenshot;
• radio mode used;
• whether normal boot/bootloader/USB mode is detected;
• steps already tried, one variable per attempt.

Never include a binding phrase, account credentials, private device identifiers, or unrelated files.

Sources and source state

• ExpressLRS Getting Started — inspected 2026-07-20. It states that production/off-the-shelf hardware should use hardware-specific Configurator targets and directs users through radio setup, TX firmware check/update, bind, bench test, and troubleshooting in that order.
• RadioMaster Boxer ELRS bench reference — user-provided source intake and controlled-RF boundary.
• EdgeTX and RadioMaster official update-page URLs initially tried on 2026-07-20 returned 404, so this guide intentionally does not name a current release file or target string without fresh official confirmation.

Related notes

• Boxer ELRS source intake and safety gate
• Drone learning map
• Drone Lab safety boundaries