Makita mitre saw ls1018l not powering up

I agree with brush changes but after that the cord and switch should be checked especially something as advanced as a soft start. The output from the switch module needs to be verified. Portable equipment power cords are notorious for having a broken conductor right at the strain relief.

when the neutral breaks a meter or a non contact tester may show voltage but no return path So the saw won’t run (a low z meter won’t show a voltage). I get corded tools quite regularly cords, brushes, switch, are the main items that fail if the brushes look good not burnt or chipped the armature is usually fine. it is the cord or switch.

I recommend using the ohm meter for those not used to or trained to test with live voltage where you can the wide prong on the plug is the neutral in the us but put your meter on one of the prongs and find inside where the cord connects and test with the ohms function no reading try the other conductor, once you have a reading wiggle the cord around at the strain relief and plug. If your reading goes from a very low reading close to a short to a thousand or more ohms the cord is broken and needs to be replaced. Test both conductors if either one reads high time to the cord. An electronic switch is beyond our scope here but since you have changed everything else if the cord tests good that would be about all that is left to change.