firebird combi boiler

Hi, Can anyone help with the below? I have a firebird C20 oil combi. Yesterday the hot water stopped working and the lock out light was on. Reset the boiler and it was calling for hot water without a tap open, couldn't get the heating to work as from what I can make out the hot water over...

Evening All I wonder if anybody on this well informed forum can assist me as I'm left scratching my head as to what is happening with my Nest controls and boiler. We have had the above Heatpac S boiler installed and wanted to install a 3rd Gen Nest. I have wired it in as below (excuse the L...