looking for some help with my neighbours boiler (Vokera mynute) it fires up for 5 seconds then looks down (red light flashes) till it cools then does the same he is having chemo treatment so trying to help him out it was losing presure before and turned out to be leaky rad which i have replaced the 3 way valve was sticking some times and heating the rads when hot water was on not all the time so i placed sentinel X200 in the new rad to clean the system but cant get it curculated because the look out . phoned a few people and been told new boiler but dew to ill health not a option . the pump and fan does run when it does fire up and does said fault on both heating and hotwater setings please any help would be greatfull