I agree the battery should be the first thing to check but not sure why you are so against considering it might be the battery...
Only other thing I think of is if you were driving the car pretty hard when you said you took it out prior and now the ECU could be acting up. My car left me stranded in a parking lot one night after some pretty hard racing. Car wouldn't even crank and it wouldn't allow me to swap tunes. I just kept at it for about an hour and finally got it to take a different tune and it fired right up.
Drivers side cam position sensor has been know to cause this same issue. Its $40-60 new. For some reason its linked with the ignition or starter some how. To test if this may be your issue jump the starter. If car fires up then thats your issue.
You have the Hellion kit correct? YES your issue is found and this is somewhat unrelated but make sure the main power harness (going to positive side of battery) that rides up under the primaries, has some good clearance between the harness and the primary. I believe it rides up very close to #4 primary. Mine is close and I have never had a issue but I was praying you didn't melt that whole harness hence why the car would have just turned off. Also sitting at idle is when it gets to some of it's hottest temps because no airflow. I blew up my AC line that way.
I do have a friend that did melt that whole harness. It was ugly.
Ok. Got a new fuse piece but that didn't fix it.
Tried jumper cables, those didn't work.
Checked all fuses in passenger kick panel and underhood related to PCM, starter, ignition, etc and they're all good.
Pushed on the clutch switch with my hand to make sure it wasn't that.
I'm lost. I still don't think its starter related because the car was running like I previously stated and it just shut off. I can even hear the starter relay clicking when I turn the key. Power stays on the entire time inside the car as well. So it's not like it's going to crank and then not being able to. It just never allows the signal to crank.
how long did u leave the jumpers on for? did u run the jumpers car to car? i ran my battery dry one day doing some installs. had the radio on for 9 hours. when i got the car buttoned up, my lights kicked on but no crank. pushed the car into the driveway, then pulled my brothers car up next to it, had the car jumped for about 10-15 minutes before i got my car to crank over and start...
Fuses always blow for a reason. Short to ground. I'd say you need to find the short, repair it, and I'm guessing do a little work to prevent heat from causing it again.
Was it the 100a side that blew? If so that side runs to your power steering, as mentioned may want to trace that wire and see if there is short that originally caused the fuse to blow.
I have seen a lot of people use battery grease on the connections that has caused it not to start, charge, stall etc. I have had some were the terminals were not perfectly clean and it caused similar issues with charging, starting etc. Clean the terminals throughly and make sure they are tight even if you think they are ok.....just do it. Jump starting through bad cables/connections will not work. Not saying this is your issue, but you should do it before buying and spending money on anything!!
when you say you are checking these fuses and such, are you using a multimeter? Do you have a good knowledge of electrical theory? If not you will be lost as you stated earlier. As someone stated earlier, the 100a fuse blew for a reason. Your car has had the motor out of it, correct? And also you stated the starter power cable went to that fuse? Using a multimeter, test the resistance between the starter cable to battery ground. If its just a few ohms its still shorted. If not i would still go straight to the starter. With the key in the run position, verify battery voltage is available at the starter solenoid(large cable from power distribution box). If Battery voltage is available there, put a jumper wire on the stud the cable connects to. connect the other end of the jumper wire to the "signal" tab on the starter solenoid. You are effectively bypassing all the electronics and security stuff. If it still wont start, your starter is toast. If it cranks then the starter itself is ok and so is the power cable, then you would need to work your way back to figure why the signal wire isnt seeing voltage when the key is turned on. This is just preliminary diagnosis stuff.
If any of this seems like too much of a hassle, have the car towed to JPC. This is likely a hobby to you, but its life to those guys.