As simple as it may sound many dyno problems can be traces back to the machine not being plugged in. There are TWO  power cables to all REI dynos.

 The high voltage cable is the large gray cable that powers the inverter and motor. This will be 220-480 volt. Make certain that this cable is connected and the power is on.

 The second cable powers the data electronics, this will have a standard household plug. Make certain that this is plugged into a known, good power source. Many problems are traced back to a faulty power strip.

You can be certain that your high voltage power to the inverter and motor is correct by looking at the inverter keypad display.  This is located on a keypad attached to a dyno column or under a lexan window on the top of the dyno. The key pad should be lit and display 0.0 hz