I have a baxi 105e combi boiler hot water fine radiators were just luke warm got british gas out changed pcb and sensor still just luke warm so he said I needed power flush(£600) friend who is a plumber took rads off and flushed then with hosepipe now the boiler works fine for hot water but when turned to hot water+c/h boiler fires up for a few seconds then turns off and flame neon flashes red any ideas what to try next