JD 690B excavator help...please!

Did you look under the engine cowling/cover for the batteries, with the larger excavators I believe they are mounted "close" to the engine. They may also be mounted inside the side door at the back. When you say start assist, does that mean glow plugs or starting fluid? You may use ether to help start, but go easy on it, not too much ether!! 2 man job, have someone crank it over while you spray a bit of ether into the intake. Also chk the glow plugs to see if they are all working. Obviously not running you are gonna get tons of lowballers. Good luck and post pics of the "beast"!!