+1^^^^
Besides charging the battery, put a voltmeter to it or better yet, get it LOAD TESTED. Most auto shops will check it for free and let you know if its good or bad...
A fully charged battery should show about 12.8 volts sitting with nothing on. Cranking, maybe drop as low as 10 volts.. (mine drops to 9 or 10 volts, but its about toast)
If you can siphon the old fuel out(un-less it was stabilized), get out as much as you can.
BTW, I did find Yamaha's RingFree in a combo Yamaha MC shop/jet ski shop, so you may not have to go to a marina...Very, very good stuff...