Hi hoping I can find some help. Ideal mini s24. Keeps locking out after working for about an hour. Reset puts boiler back on makes all the right noises but no spark or ignition. Turn off main switch for a while, turn back on and will ignite for another hour. In lock out 3 lights are as follows both green(1 and 3) flashing slowly and red light in middle on solid. Had a boiler installer pal out, he changed thermistor,seemed to work but only that night. According to book lights point to pcb? Want to be sure before ordering one as not cheap and don’t want to be changing parts that are not to blame. Had a look at pcb and looks good as new. Any help would be appreciated thanks.