I neeeed chainsaw help?

year old JCB , used it yestersday to cut down a old tree stump, which was rotten a bit , petrol was ful , i forgot to check the oil level , it was low . so anyways i started to cut into the tree , as soon as i reved the engine it stopped, with the chain going round .it was raining aswell yesterday , no change their ( suppose to be summer) . cleaned it last nite , filled up oil , gave it another rewing today but it the engine stopped as soon as i stopped the rewing straight away . is it dirty that has gotten into the spring chamber or fuel mix ? 5 stars awaiting who ever wins