What are the causes of the main relay failure in Audi A6L?

[AvaAnn]

Relay failure can be caused by the following reasons: Insufficient power supply: Power failure, severe battery depletion or plate sulfation, short circuit, poor contact between battery terminals and cable clamps, loose or poor contact in the starting circuit wiring connections, etc. Short circuit: Poor contact between the commutator and brushes, open or short circuit in the excitation winding or armature winding, grounding of insulated brushes, open circuit, short circuit, or grounding of electromagnetic switch coils, or burnt contacts, etc. Ignition failure: Ignition switch failure, loose wiring or poor internal contact in the ignition switch. Starting system circuit failure, open circuit, poor contact, or loose connections in the starting circuit wiring, etc.