Hang on gozer7, the thruster is not hard wired straight to the battery (like a starter motor), it passes through that 150 amp fuse (you haven't told us if it is ok yet?) we spoke of earlier, next to the switch under the starboard berth that mlull indicated.
My reading of the circuit that came with the Side Power manual in the Ranger provided kit of manuals (possibly also available on the internet) shows that the joy stick panel is also powered via an electronic interface box mounted with the thruster motor, and ultimately over this large 150 amp cable, 150 amp fuse (possibly blown) and large red switch (under the helm side berth). If this 150 amp fuse is blown you wont have power to the thruster or joy stick.
If this 150 amp fuse is blown, check that you can turn the thruster propeller by hand. If you can't, the bearings are probably siezed with rust from water ingress, overloading the motor and causing the big fuse to blow. If you can turn the thruster propeller, replace the fuse and try it.
If this 150 amp fuse is ok you are going to need a voltmeter from here on. The places where you should see +12V are :-
. thruster side of the 150 amp fuse
. terminal 3 (motor side) of the Electronic Interface Box (located with the thruster)
. terminal 9 (joy stick side) of the Electronic Interface Box (there is a 1 amp fuse inside the box)
Note, I would leave the above two measuring points until after you dont find +12V at the next point because they are a bit hard to get at.
. pin 4 (red wire) of the four pin connector at the joy stick.
Cheers
Graham