There is actually a section in the manual to get the M-Tronic adjusted to optimum power more quickly.
First see if it is out of gas. Then pour all the gas out and look in the tank to see if the line is broken. If this is all good go back to the exhaust port. If you can see piston move up and down thru the exhaust port you should be able to see the ring. If the piston is scored, scratches or lines up and down on the piston and across the ring, it got to hot. The cylinder will be scored too causing it to loose compression. If the piston looks good, smooth with no scratches, the cylinder and piston are probably ok. The crank shaft seals could be bad causing a lean condition that could cause it to stop running. You have to do a vacuum and pressure test to check the seals. Sometimes the coil can go bad. You can start the saw and use it and it will run fine but when you shut it off it won't crank until it cools off. The only way to check that is to put a new coil on it. If it fixes it you know the coil was bad. If it doesn't fix it you know the coil was good. Now you have an extra coil. Pulse tube could be leaking causing it to stop running because of lack of gas. Fuel pump diaphragm in carb. could have a hole in it. Also there is a small hole in the cover over the fuel pump diaphragm. Fine dust and dirt can inter the hole and build up over time and the diaphragm can't move enough to pump gas. This is on the bottom of the carb. It has small philips head screws at the four corners of the cover. Remove the cover, gently remove it without moving the diaphragm. Blow the dust out. Remove the diaphragm and blow thru the fuel intake tube while you push down on the needle valve arm opening the valve. If you can't blow through it something has stopped up the needle and seat. Remove the needle, arm, and spring. Then blow it out with carb. cleaner an reassemble. If none of this works buy a new saw.
no valves