While electric bicycles seem complicated in nature, there are only a handful of extra parts compared to a traditional pedal bicycle. By understanding each of these components and their function it will help determine the cause of any problem you might have and how to get it resolved.
The motor is what propels you, it can be located in a wheel or at the crankshaft. Historically it is rare for a motor to go bad but it still can happen.
The controller is the brains of the operation. It is similar to the circuit board inside a computer. The controller is typically hidden inside the frame in an aluminum box with wires coming out of it.
The battery supplies voltage to the controller (not the motor), which powers the motor. When people have problems with their bike, they almost always assume it is an issue with the battery, however, this is not always the case which is why it is important to trouble shoot the entire system.
The cables transmit the power and signals between the different components of the bikes. It is possible for cables and their connectors to become damaged and loose. This is the cause of most problems with an electric bicycle which is why it is important to examine them and make sure not to damage them.
The LCD screen displays your speed, assistance levels, and other information used when riding. If there is an issue with the LCD screen not turning on, most people assume it means the battery is not charged however from the above diagram you can see the true cause could be any of the items above except the motor.