That may not completely be the case. Have you charged your battery? That 'click' might just be the sound of the motor not being able to pull the piston back against the spring.
Charge your battery, or if you have another rifle, try saucing it in there and seeing if it fires.
That'll isolate your battery as either problem or not, and you can move onto the gearbox.
Edit: loljk you just said you charged the battery
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