TBS Lucid H7 Bricked After Arming with SD Card — No USB/DFU/COM, Solid Red LED Only

ArduCopter
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Summary:
My TBS Lucid H7 flight controller was working normally until I armed the drone with a microSD card inserted. Immediately after arming, the board began power cycling. After removing the SD card, the board now powers up with only a solid red LED and is completely unresponsive. It does not show up in Device Manager, and I cannot reflash it.

System Context:

  • TBS Lucid H7 Flight Controller
  • ArduPilot firmware (previously working fine)
  • Powered by 6S battery
  • RFD900x telemetry radio
  • External GPS and receiver connected
  • ESCs emit “no signal” tone (indicating no output from FC)

What Happened:

  1. I inserted a small microSD card into the flight controller’s SD slot (256MB).
  2. The board powered on as usual and connected over telemetry.
  3. I was able to upload missions, change parameters, see GPS lock, artificial horizon movement, and battery status — everything worked normally.
  4. I attempted to arm the drone. As soon as I armed it, the props spun briefly and the flight controller power-cycled.
  5. This happened multiple times in a row while attempting to arm, all while behaving normally in between each arming attempt.
  6. I removed the SD card, thinking it was the only thing I had changed.
  7. After removing the card, the flight controller now only shows a solid red LED on power-up.
  8. It no longer appears in Device Manager (no COM port, no DFU mode, no unknown device).
  9. Holding the boot button while plugging in USB makes no difference — the board remains with a solid red light and is not recognized.
  10. I tried multiple cables, USB ports, and PCs with no change.
  11. Re-inserting the same SD card does not resolve the issue.

Reflash Attempt and Error:
When I try to reflash the board using Mission Planner by clicking on “Copter” to begin the firmware install, I get the following error message:

Failed to detect port to upload to (Unknown VID/PID or Board String)
Please try Disconnect/Reconnect and upload while on this screen

This happens even if I hold the boot button while plugging in USB. The board remains in this unresponsive state with no indication of connection in Mission Planner or Device Manager.

Request for Help:

  • Has anyone experienced this issue with a TBS Lucid H7 or similar board?
  • Is there a known method to recover the board when it does not appear in DFU or USB at all?

Anything is appreciated, I am stumped

2

Booting into DFU mode does STM32CubeProgrammer show anything under Target Information after selecting USB and Connect?

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Update:
After a lot of trial and error, I was finally able to recover the board. I’m sharing the full solution here so that anyone else who ends up in the same situation can follow the steps.

Solution: How I Recovered My “Bricked” TBS Lucid H7

I was never able to get STM32CubeProgrammer to work reliably. Every time I tried to disable Read Out Protection, the board would immediately reset and drop the connection before I could erase or flash anything. After enough failed attempts, I decided it was time to try something else — literally anything that wasn’t STM32CubeProgrammer.

Since Betaflight Configurator has always been stable for me, I decided to try flashing Betaflight firmware to the board just to force a full chip erase. Once I opened Betaflight and plugged in the board in DFU mode, I noticed that Betaflight recognized the DFU device (shown in the top dropdown as “DFU”) even though auto-detect didn’t work. I manually selected a board and firmware version, checked the “Full chip erase” box, and clicked flash. To my surprise, it worked — Betaflight flashed successfully, which meant the board had been fully erased and was back in a functional state.

From there, I moved back to Mission Planner and used the “Load Custom Firmware” button under Initial Setup → Install Firmware. This time, I used the .apj file from ArduPilot’s official build site:

I did not put the board in DFU mode for this step — I just plugged it in normally. Mission Planner detected the COM port and successfully flashed ArduPilot over USB. I avoided the .hex file because I had previously tried flashing it, which caused Mission Planner to crash and forced me back into DFU mode. Using the .apj file over USB was much smoother and didn’t require any special drivers or mode switches.