Caution: Before you remove the motherboard, be cautious of the many capacitors throughout that could cause serious injury. Use a discharge probe to safely rid the capacitors of dangerous charges.

Wearing electrically insulated gloves and rubber soled shoes while working with and near the capacitors ensures greater safety and protection against electric shock. See iFixit's Project Safety page for additional safety information.

There are 5 fuses total, make sure to remove them from the holder and check for continuity with a multimeter.

If all test Ok, you might need to have the Power board replaced.