No. CPR and an AED work together and neither replaces the other. They do different jobs at different stages of the resuscitation process.
CPR keeps oxygenated blood circulating to the brain and heart while the heart is not beating. It does not restart the heart, but it delays the onset of irreversible brain damage and keeps the heart muscle responsive to defibrillation. Without CPR, the window in which an AED can work effectively narrows quickly.
An AED delivers an electrical shock to reset the heart’s rhythm when it is in ventricular fibrillation or pulseless ventricular tachycardia. This is what CPR alone cannot do. The shock is what restores a normal heartbeat.
The correct sequence is: call 999, start CPR immediately, apply the AED as soon as it arrives, follow the AED’s instructions, and resume CPR straight after each shock analysis. Do not stop CPR while waiting for an AED, and do not stop using the AED once it arrives.