A couple of troubleshooting tips:
Did you connect the motor properly? If you reversed the cables and connectors it won't work.
Then check if your battery is fully charged.
What strength spring is in your gearbox? If the spring is heavy (<m120) it will require a strong motor and battery to pull it back.
Every word ever written will fall short, of it's intent
Even sung, or spoke, or screamed, they will betray what they had meant.