That is a bad situation, have seen alot worst , those dead tracks buried under the mud / water has got to have a lot of suction going on , and it you try to go back wards it looks like it will pull right into the roots of that tree , the longer it sits there the more in will probally sink unless you get lucky and it's on top of some roots, also the longer it sits the more chance you have of water coming up and floodig the engine , I would think at this point from the level it sits the fuse panel has burned out the power wires off the back of the fuse panel that are not on the accesory side and live all the time and that is why you can't get it running , but I doubt from the way it looks that if it were runing at this point that you still wouldn't get out ---------I would think that the machine would stay on rent till it is back up running and rentable at the rental houses yard , so time is money , then longer it sits the more it's going to cost and the greater chance of more damages , without the motor running I don't think you will do any good with chain falls or comealongs unless you hire a crew of Egyptian pyraid builders , I think you will need an excavator to lift it up and get wood under it , then try to pull it to shore , I'd almost wonder if it is best not to call the rental house if you can come up with a plan on your own , I doubt seriously that they will come out and get it out free of charge and if you can get it out and get it running and power washed clean on your own without telling them what happened you may come out alot cheaper as if the wiring is burned at the back the box the right way to fix it is a new harness as the fuse box is wired into it as an assembly , I can tell you how to repair the wires with out replacing the harness but the rental house probally wouldn't go for it as the machine looks farely new and they will probally stick it to you'll pretty good