Possible causes of electrical failure in a car:
1. Battery:
* Discharged or defective
*Wrongly connected
* Worn terminals
2. Alternator:
* Does not generate current to recharge the battery
* Diode bridge is faulty
* Damaged drive belt
3. Starter:
* Solenoid faulty
* Worn brushes
* Incorrect connection to the electrical system
4. Fuses and relays:
*Blown fuses
* Faulty relays
* Oxidized or loose contacts
5. Wiring:
* Broken wires
* Short circuits in wiring
* Poor connections
6. Electrical control module (ECU):
* ECU failure (rare)
7. Ignition switch:
* Faulty ignition switch
*Worn or damaged key
8. Loose connections:
* Incorrect or loose connections on battery, starter, ECU and other components
9. Water Damage:
* Damage due to water exposure to electrical components
10. Electromagnetic interference (EMI):
* Interference from nearby electronic devices (eg mobile phones)
Contact a qualified mechanic to diagnose the exact cause of the electrical failure. This will ensure a safe and proper repair.