a RAK4631 with Arduino bootloader mounted on RAK19007 has been running Meshtastic for several months.
Today it suddenly stopped sending telemetry data approximately 2 hours after I connected it to a new “smartphone” USB-C charger that I haven’t used for charging my nodes before.
Now only the red LED on the RAK19007 lights up (blue & green LED stay off) and the board is no longer detected by my Linux machine (no serial or block device, no entry in kernel’s log when plugging in).
Pressing the reset button seems to be ineffective. Thus, I can not re-flash the firmware.
I suspect that the issue was triggered by me connecting another USB-C device to the second USB-C port of the charger. I can’t tell for sure but the telemetry recordings (captured via Meshtastic’s MQTT integration) stopped at a similar time I connected the second device (laptop).
Any ideas how I could further investigate this issue?
Has anyone ever had a similar issue before?
I have used WisBlock BaseBoards with all kinds of USB chargers (including fast chargers and chargers with additional 12V output), but I never experienced that the Base Board got damaged.
What you can do to get more information is to test the voltages on the pins VBat and VDD:
If Vbat is between 3.2 and 4.2V, the charger chip should be ok, else the charger chip is damaged
If VDD is 3.3V, the voltage regulator should be ok, else the voltage regulator is damaged
If any of the two is not ok, you damaged the Base Board.
If both seem to be ok, try to force bootloader mode on the device with double-push reset button. If it shows up as USB device, then the application (Meshtastic firmware) is not working properly. In this case you can try to reflash the Meshtastic firmware. But do a flash reset before. See the Meshtastic documentation how to do this.
Then the voltage regulator chip is broken and you need a new Base Board.
If the voltage regulator is broken, there is a chance that the Core is burned as well, but you will know that only if you can test with another Base Board.
