An iCloud Activation Lock is designed to keep your information safe and secure in the event of a theft. It allowed iPhone, iPad, Apple Watch and Mac owners to secure their devices letting them wipe or lock their device remotely from the iCloud website. Whilst a great security feature for iPhone owners, it causes an unintended consequence on people who buy pre-owned handsets - because often when wiping a device, the iCloud account remains on the handset meaning you are unable to access the homescreen.