Yeah, good luck getting anything for free out of a gunsmith who might have worked on the gun for someone else 7 years ago before you even owned it.
No reason to send it anywhere. M&Ps are very simple to work on.
Likely all your issues are spring related. Personally I experienced all the following, and likely one or more of these applies to you:
No strike: Could be one of two things:
1) If you have a light recoil spring with a lot of miles on it, and it is now very light, you could be just a tad out of battery. You will still get a click, but no strike at all. This happened to me with a high mileage 11lb recoil spring, and a stock striker spring. The recoil spring and the striker spring are "fighting" each other as the pistol goes all the way into battery, and if they are not balanced you can end up slightly out of battery. The fix would be new recoil spring. I settled on 13lbs when I was shooting the M&P a lot.
2) If you have a lightened sear spring that is additionally either high mileage, or dirty, the sear may not be resetting at all. The little spring under it is the only thing that presses it up, and if it is weak or dirty, there is a chance the sear is not resetting, so it is not grabbing the striker as the gun goes into battery. Symptom would be "dead trigger": No click, no strike. The fix is either to clean the sear housing (under the sear) and/or go to a heavier sear spring. After I let mine get super dirty the first time, my solution was to use a stock sear spring and clean under it every few thousand rounds... never had the issue again.
Light strikes:
1) Could be the same as #1 above; just not quite to the point of getting NO strike. Fix, again, would be a new/stronger recoil spring.
2) You could have an aftermarket lightened striker spring that is not hitting your primers hard enough. Fix would be to go to a stock striker spring, or start using Federal primers.
M&P parts are super cheap, and you could likely restore everything into to stock for less than 100 bucks if you just wanted to go that route.