Today I arrived on site Initial Assessment: Investigated a no hot water complaint for the DHW zone. Problem Identification: Discovered the combustion device had no power. Safety Check: Noted the safety switches were tripped. Upon arriving at the property. The client explained to me that since yesterday there is no hot water in the house. The client mentioned that she wanted to know the cause was related to the maintenance that was done recently. I proceeded to verify the HWH. I found that the combustion safety device had no power. I also found that the safety switches were tripped. I proceeded to check if there was any power switch off. I found the power switch in the boiler room off position. I put it in on position. I started the HWH. The HWH began to operate normally. I showed the client what was the reason that the HWH did not heat the water. I explained to the client that the cause of the failure has nothing to do with the maintenance we recently did on the property.