Hi All, Firstly, I'm not a plumber. Management pushed me to disconnect an upstairs rad and flush it. After reconnecting it the boiler would not start correctly. The fan would spin up and then it would click off, then repeat. I realised it wasn't happy so turned off the system. I re-checked the system for air (there wasn't any)and the only valves I turned off/on were the TRV and lockshield either side of the rad. I then turned the system back on but got no signs of life from the boiler. The boiler has a bi coloured LED (Red/Green) and a liquid crystal display that shows errors, or in normal working conditions the temperature. Anyway, no signs of life. The connector panel below the boiler has 240V on the supply line and the adjacent connector has 240V when it gets demand from the controller. On the PCB the fuse is fine and the 240V is getting to the PCB via the main double pole switch on the front panel. I carefully removed the PCB and looked it over. A couple of the electrolytic capacitors were mildly bulging but apart from that it looked fine with no signs of heat or dry joints. The ******* annoying thing is that prior to me flushing the rad the system has been fine and without any issues. Any advise would be most welcome. Thanks.