Hi, our Baxi Combi 105he began playing up about 4 weeks ago. It delivered hot water and CH only intermittently, the flashing light indicating a fan fault when it wasn't working. Now it has become completely unresponsive, no LEDs light up to indicate a demand for hot water or CH or any sort of failure and it makes no sound. There must be power as the LCD is working. Any idea what's up, what I can do, and what it might cost? The cheaper the better, cash strapped student nurse asking! Cheers.