stihl ms 170 iratic starting?

i have a ms 170 stihl chainsaw which refuses to start, i rebuilt the carb with new genuine parts, e.g. new diaphram and gaskets, i cleaned the exhaust out, i replaced the spark plug, i also drained the fuel out and cleaned the tank, the fuel line from the tank to the carb is clear, is there an elecric module that controls the engine that could be the problem,