Ahhh, the joys of a 240 with a dead battery, BTDT. As you probably already know, this machine is a pure SOB to jump, and what you'll learn is that it's really brutal in cold wether.
You need HEAVY jumpers, not the automotive ones, and you manage to stuff the + jumper onto the battery from the left sode of the machine. Put the - jumper onto the frame of the machine itself. One of the loader mounting bolts usually works well. Hook up the other end at the Suburban, and let it charge the Yanmar for a few minutes before trying.
Use the comperession release, it's a lever below the left side of the dash, about 5/16 round rod. It should turn 90 degrees to the left for decompression. If it doesn't turn, don't force it or you'll bust something. Follow the rod to the intake manifold, and shoot everything linked to it with penetrant, it will free up in a half hour, usually.
Hold down the decomp, and spin the machine over for a few seconds, and then release the lever, and she should wind up.
Since it's been sitting, it might be a good idea to bleed the fuel system before trying to start the tractor. If you don't have good flow at the pump, replace the fuel filter.
This machine is also famous for start solonoid problems. Fortunately a replacement is available thru NAPA for around $30-, far lower than the John Deer dealer will charge for the replacement. Actually NAPA can also provide all the filters for this machine.
When you get the machine running, put a voltmeter on the battery, the alternators on these machines SUCKed. If you don't have a good alternator, a Delco replaces it easily.
Since it's warm, the tractor should start fairly easy.
If you're going to use the machine below 30 degrees, plan on a new battery every 2 years, or starting assist.