So, I kinda blew it...

I picked up a turbo 300d starter in the junk yard for 15 bucks and had it tested and it was good. I pulled mine out and just to see hooked it up to a good battery and with no load it wouldn't crank for but a few seconds.

I put the new(er) starter in, and I was also going to change the ground wire and the positive to battery. Now, I this is where I'm confused. One way I hook up the wires the starter will just crank and crank and the solenoid won't click on. If I hook it up the other way the car is dead, no electronics at all. Did I fry something electrical? Any help here? The way the I hook it up when the starter cranks forever is + battery to the post closest to the starter. I have the solenoid wire hooked up and if I short to that I can get it to crank the car over, but without glow plugs and not being plugged in I'm not to sure I should expect it to start. Any help would be great, thanks. Also if I'm too vague...just tell me to clarify.
-Nate

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'82 240D, 4-speed, 617 turbo engine