In reference to removing lockout after a power cut, the Photon installation manual says "The limit control LC3, which operates at a higher temperature setting, switches off the burner to a lockout condition requiring a thorough check of the heater and a manual reset via the LC3 limit control body followed by the lockout reset switch. A cooling time of about 3 minutes is necessary before resetting." so the internal LC3 green reset button will need to be used to take the system out of lockout state. Please see the Photon Installation Manual for more information.
Our site had a power cut and now our Photon heater is in lockout, what do I do?
Information on Reznor's range of warm air heaters