You know the suggestion of checking videos online or in forums is a good one. It might be as simple as checking power being fed to the motor that feeds the wire.
Randy brought up all good ideas, if you do indeed have power. Anytime mine has not fed wire, checking the tip is a no brainer, but making sure there isn't to much tension or if something is preventing the wire to slide freely through. I had a kink one time. Always easy to clip the wire before it goes into the sleeve, operate the trigger and see if it works prior to being fed through the sleeve. Just keep working the problem backwards would get you there.