Potterton Suprima 60 with replacement PCB board has a intermittent fault?

The boiler runs for a while (green light constant) , goes into standby mode, when it tries to relight (orange and green flashing) fails to relight. Turn off power for a few minutes, turn on power (orange light)
followed by (orange and green flashing) boiler lights and constant green light shows.
After a while goes into standby and will not restart.