No hot water on a Worcester Bosch 30i erp combi boiler water running hot and cold diagnosed fault

This Worcester Bosch 30i combi boiler had the water running hot and cold, I turned up and tried the tap for myself. The temperature began to rise very quickly and the boiler reached temp and cut out making the water from the tap cold. In this video I explain what’s happening in this situation, how to diagnose and what part to change… Hope this helps ✅