1. Sewage level switch.
2. High voltage lines are interrupted.
3. The laser tube is broken or burned.
4. The laser power supply is broken.
5. Water circulation “including blocked water pipes and non-working water pumps”
6. The waterproof line is broken or the contact is bad.
7. There is no 220V input to the laser power supply.
8. No signal from laser power supply “The signal cable is broken and the connection is bad, the relay that controls the light output is broken, the board is broken and the connection is bad.”
9. The second inline shaft is stuck.