Just replaced my dead hard drive with a 2TB also replaced fan since I had it apart. Plugged unit into AC adapter and two lights inside Tivo Roamio alternately flash. One blue and one green.The unit wont start. Checked output voltage on adapter and its 12.1 volts. So I have a AC adapter for my Western Digital External that reads 12.25 volts and I plug that into the Tivo and it works but the plug is a different style that wont stay in very well. The Roamio did work prior to the HD replacement but always froze on start up screen. I will order new AC adapter power supply but perplexed why the old one wont power up the unit. Any thoughts?