When your car shows the car and lock light it means that your vehicle's anti-theft system has been triggered. This is a standard feature in most modern cars. The system will prevent the engine from starting if it detects that a different key than the one you normally use to open and start your car is being used.
This is done to keep the car safe from thieves and to ensure that only you are driving your vehicle. It can also be triggered by tampering with the car's doors or windows. This could include trying to slam a door shut or inserting something into the ignition. This can be a serious problem if you are not aware of the situation and do not respond quickly.
In most cases this warning is triggered by a bad key fob or a low battery in the key fob. This can cause the immobiliser to not recognise the key fob and therefore prevent it from starting the engine. If this happens it is important to replace the key fob as soon as possible.
Alternatively, this can be caused by a problem with the immobiliser itself. If this has been damaged by water ingress or damage the immobiliser will no longer recognise the key fob and therefore prevent it starting the engine. This can be an expensive repair, so if this is the case it is best to get in touch with your dealer for further information and guidance.