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The square black box closest to you is the oil burner transformer, this one has 10,000 volts it is best to leave it alone, it will literally knock you on your ass if not worse.
Newer ones have more vlots.
behind that is a Old style Honeywell Cad Cell Relay with a red reset button, this type of cad cell relay will let you push the reset button until you blow up your house, I recommend only pressing it once, if it does not start call a pro. 

Honeywell Cad Cell Relay