The symptom
After a switch command · remote or manual · a breaker's LEDs go completely dark, and it will not turn back on. Remote commands do nothing, and the manual toggle does not restore it either. Other breakers on the same panel behave normally, so this is not a bus or controller problem.
What it likely means
Dark LEDs mean the breaker's electronics are not powered or have failed. The likely causes are:
An internal electronics fault · the breaker's control electronics have failed and the unit needs replacing.
A loose or faulty neutral or terminal connection · the electronics lose their supply. A terminal that sits looser than its neighbours is a strong hint.
Incorrect RS485 wiring · the red and yellow communication cables wired wrongly at the breaker.
A breaker under significant load may also have tripped protectively · but a protective trip does not turn the LEDs off. Dark LEDs point to a power or hardware problem, not a safety trip.
What you can do yourself
Stop switching it. Repeated on and off attempts will not recover a dark breaker and may make a marginal connection worse.
Look, don't touch. With the panel cover open only if you are qualified to open it, compare the breaker's terminals and its RS485 wiring visually against its neighbours. The full visual checklist is in On-site visual checks · what to inspect on a Hybird panel.
Photograph it. Clear, close photos or a live video call showing the breaker and its wiring help enormously with remote diagnosis.
Treat the circuit as out of service. Whatever the breaker feeds is off until the fault is resolved. If the circuit is part of a shared system fed by several breakers · ventilation is a common example · the loss may not be immediately obvious, so check the connected system directly.
The next step is an electrician
All three likely causes need a qualified electrician: checking and re-torquing terminal connections, verifying the RS485 wiring, or replacing the breaker are live-panel work. Arrange the visit rather than continuing to troubleshoot remotely · once the LEDs are dark, there is nothing further that can be done from the platform.
Summary
Dark LEDs on an unresponsive breaker mean the electronics have lost power or failed · an internal fault, a loose neutral or terminal, or incorrect RS485 wiring. Stop switching it, inspect and photograph it, treat the circuit as out of service, and get a qualified electrician to the panel.