You have two possibilities.
1. The switch is bad and must be replaced.
2. the motor is bad and the complete saw needs replaced.
It is going to be hard to find someone that will work on this for you because we repair shops, are required to use a "High-Pot" tester any time we work on electrical equipment to make sure that there are not electrical leaks...and...almost no dealership has one because they are very expensive and most of the time these electrical products cost more to fix them than they cost to buy new and parts are nearly impossible to get for them.
If you want to check the switch you can, but my advice is to throw this thing away and buy a better brand .
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