Starter enable relay has been replaced. Dash definitely needed to come off. It'* directly behind the insrument panel maybe a few inches below the defrost vents. Mounting bolt above it. Installed it and put my car back together enough to feel safe an airbag wouldn't go off in my face. Car started up nicely twice. Turned it off satisfied, put the car back together a little more enough to leave it for a week during the test phase. Went to start again, nothing. Not only that, but a battery down to 8 V and rapidly dropping. Given the doors were open so the interior lights were on for 20-30 min between, but that shouldn't have been enough to drain the battery after a few recent starts. I should have probably let it run longer. The positive battery terminal is beginning to strip as well so I will need to replace that. But it was a solid enough connection to sit in the parking lot. No clicks when jumper cables hooked up either.

So in other words, seems it was not the relay. Where to go next?

its too bad that relay is so ridiculous that would be a good spot to check stuff. i soppose i would check for my ground on the side of the park/n switch that goes toward the relay. it may or may not read like 12v with the key off but should go low if the key is turned and the pass key mod is doing its job. if you have that then you could check for 12v between the ign and the relay if youve got that and the realy works you should have 12v going toward the little wire on the starter.

as far as the battery at idle the alt doesnt make much power, you have to leave the car running for ever to recharge after starting the engine a couple of times. also having loose or corroded terminals can cause the issues your having too. i think if it were me i would just replace that pos wire too the alt, and put some dielectric grease on there to keep the corrosion from returning

I wasn't able to test any voltages today since my battery is dead, and it seems impractical to do so with jumper cables attached (although it may happen soon). However, I did finally have a chance to get under my car to check out the starter. Connections were fairly tight, probably not as tight as they should be, but when I went to tighten them I noticed the bolts were spinning in the starter. So the other end of the bolt must be stripped. I called Autozone and they have one on hold for me to pick up tomorrow as a warranty replacement.

The whole front of my engine and starter were also soaked in oil .. probably from the valve cover gasket I just replaced. That amount of oil may have made the starter go bad? I'll make sure to clean it up before I take it in. Hopefully this will resolve issues.

I also noticed today while the jumper cables were connected that I do hear a "release" sound after I let the key return the from starting position. I hear the relay charging up from a different spot, so it'* not the relay. My guess (and completely a guess) would be that it is the starter moving into position with the flywheel but not receiving enough current to spin.

I also replaced the battery post as suggested. Battery cables are not available at any local parts store. It'* one of those dual cables where one goes to the alternator and one goes to the starter, and then there is a separate cable which appears to go through the firewall somewhere (but I didn't really look into that one as it doesn't seem to be important at this point. I'll try calling the dealer Monday, but I can't imagine that will end well in terms of pricing. I can't seem to find one available online, but if anyone else can I would take the time to order this one.

The other end of that cable is under the maxifuse/relay cover. This one powers most (if not all of) of your electronics.

As far as finding the GM-recommended battery cables, your best options are less-used ones from a junkyard, or new ones from RockAuto. They're sold under the AC Delco brand.

If you don't mind cutting and splicing, generic battery cables from any parts store will get your car running in a pinch, though I've had strange things happen with Frankencables.

it doesnt sound like the cable at this point, you could just clean up the ends and put dielelectric grease on it. it seems like your starter is the cause of your issues. i dont think the oil would cause your terminal to come loose inside, they dont require popeye force to stay put

Well, it appears to have been the starter. I put the one in, jumped it, and started right up twice. This blows my mind a little bit. The starter connections were spinning in the holes, but without making moving them around sometimes it would start and sometimes it wouldn't. I guess I shouldn't determine it "fixed" for a few weeks. Upon starting I found my donut exhaust gasket which has been slowly fading is now nearly completely blown. That'* tomorrow'* project. Fortunately, I'm a college student so I can go some time between repairs if need me without needing to have a car.