Glowworm micron 50ff?

Hi, I have just had my circuit board and thermistor changed on my boiler, I supplied the parts, the led on the board are the green ones, The boiler wont fire up. The sequence it goes to on led is burner led flashing fast 8hz. the board is 2000801990 model and thermistor is 2000802635. Any ideas anyone . Thanks.