1, Go to the Headend and Confirm if  the rack is powered if not check the UPS by the left or right side the rack and check if there is power coming to it. 

2. If no power, carefully trace where the ups is been power.

3. If is been power from inverter, check if the inverter is on.

4. If not turn on the inverter and check if the power has supply to the UPS.

5. Once the power is  supply to the ups turn on the ups power button located at the front of the ups and check if the Rack is powered.

6. If no, look for a device label power conditional at the bottom part of the rack and turn power button on. by this time The rack will come on.