Dyson V7 not working. Is it motor or battery?

[hw_user]

My Dyson V7 stopped working. I want to know if it is my battery or the motor is bad.  I did two tests
1. I pulled out the battery. I can see the trigger button and the + and - slots where the two tongues from the motor side inserted into. I inserted a piece of wire into each slot and meter the voltage. There is no output with or without the button pushed. The vacuum is plugged in all the time. I think the battery is at least somewhat charged. I should see some voltage. Do I have to insert a piece of metal similar to the tongue to see the output?
2. I use a DC power supply to provide 21 volt (I think the battery is 21.6V) directly to the two tongues. But the motor is not turning. I think the trigger is on the battery side. Unless there is any hidden switch, the motor should turn.
Can anyone help?