"If it isn't broken and you don't know anything about it, don't fuck with it" is a rule to live by. There's no reason a stock Classic Army gun should need any servicing out of the box.
So how about just going back to the person who did the work and explaining it. It worked when they received it. It should be working when they give it back "repaired".
And you didn't blow your motor. You probably just blew your fuse.
If you want to do it yourself, go to mechbox.com and watch some videos. Armalites are some of the easiest guns to work on.
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