Saturn Ion no crank/no start
 

So, my car will not start... I've been fighting it for a while but finally decided to ask you guys for some help...

It's been sitting for a while, so the battery is definitely discharged (could have internal short or something I guess), but even with a jump pack it won't start back... The same pack would start my wife's Ion with a weak battery, and started my Redline which had sat for almost a year with a dead battery...

When I hit the key, I can hear a solenoid click every 2 seconds and the engine will turn just a little(the belt moves about 1/8" with each click)

I examined the starter and found some really corroded terminals and the one unshielded wire from solenoid to starter was badly corroded and crumbling, so I replaced the starter with the spare one for the Redline... The one ground I could find on the engine looked okay(but very greasy) and the ground from the battery to the trunk floor looked solid...

I'm a little lost here... I'd like to have it capable of starting so that once my wife starts working I won't be stuck absolutely having to walk/bike to work...

You've started the troubleshooting already. Next check all your power connections really well. Try to wiggle or move the connections. If they move at all you have a bad connection and that can contribute to non-starting. Corroded terminals either need to be well cleaned or replaced.
If you have a meter, have someone turn the key for you while you measure the voltage across the battery. If it drops below 10 volts while trying to start, that's a good indication of a truly dead battery. If you have a dc amp clamp you could also see how much current is be pulled on start. I don't know the specs for a Saturn, but you may be able to look that up online. You may be able to recharge the battery either by jumping it with another vehicle and then just letting it sit there while the other vehicle runs for ten or fifteen minutes. Of course you could just try a battery charger or another battery too. Since the motor does turn, that eliminates your actual starting electronics and the starter itself from being the culprits(usually). I have actually seen a starter with a short in it draw down the battery and allow the motor to crank just a bit, but you said that you replaced the starter. Good luck with the fix.
JJ

Corroded battery cables act exactly like a dead, dying, or discharged battery. Remove both cables, clean the connections at both ends, and check for corrosion between the cable and connector at both ends of both cables. If you see any sign of corrosion in the cable, replace both cables.

Get a battery charger. A six amp charger is plenty big enough. Fully charge the battery, then try to start the car.

Try removing the serpentine belt. I have heard of a/c pumps locking up and preventing the engine from starting. Worth a shot.

I would also disconnect the battery and check resistance from + to ground on the starter. Could be losing power to ground and skipping the starter.

I hooked wife's car up to mine with jumper cables for 30 min or so, charging the battery as best as I could, and with the other car hooked up, it started, with a short squeal(sounds like sticky bendix in starter), but as soon as cables were unhooked it failed to start again, even with the jump box plugged in...

Not sure if bad cell in battery or just severely discharged, or bad cables somewhere between battery and underhood fuse box

Could you try the battery from your wife's car?

I also vote battery.

I have had my fair share of deadish ones.