The first step is to make sure the power cable connector is properly connected to the power port. Sometimes these can come unplugged when things are moved around.
The second thing to check is that you are using the correct power supply. The MyWirelessTV 2 should have a power supply that has the following specifications on the label 5V DC 2A.
If it is still not working you may need to have the power supply checked at a local electronics store. If your MyWirelessTV 2 is less than one year old give us a call or open a support ticket and we can send you a new one after some more troubleshooting.