Car not turning on after brake job

Hey everybody! I've got a weird one.

I just did a fairly big overhaul on my 2005. New catalytic converter, parking brake cables, pads, shoes, rotors. I also removed the front seats to clean underneath. And I think that may be where I screwed myself.

The car isn't turning on. Auxiliary battery has charge, but it won't start. I didn't disconnect the battery before rmoving the seats, which may have caused the SRS to get finicky, but I'm not sure.

Behavior: key out of the slot (Smart Key car) and it beeps and gives yellow "no key light" when you try to start it. Key in the slot and it doesn't pop up that light, but it doesn't do anything upon hitting power.

The relays click as expected when I get in. It just isn't being alive.

 

Nothing at all. I've held it for as long as 45 seconds and no dice.

 

Update on the car.

I let it sit all night with the negative terminal disconnected. Reconnected the negative terminal, and nothing has changed.

The red immobilizer light flashes as expected when the car is off. Pressing the power button with the smart key out of the slot results in a yellow "No Key" light. Pressing it with the fob in the slot doesn't give the "No Key" light.

I tried toggling the Smart Key switch below the dash and re-trying, but nothing.

I switched to the other fob (both original to the car and worked a week ago). Nothing.

Fob batteries are good. They each emit the red light when a button is pressed.

The dome lights, headlights, "Key in ignition with door open" alarm, door locks, and hazard lights work fine.

The AM2 fuse is not blown (unfortunately; I would have been okay with buying another inverter pump).

The behavior basically mimics the AM2 fuse issue, which has me stumped.

 

The relays don't particularly sound any different than usual.

What's getting me is that the repairs I did weren't electrical. My head tells me there's no way it's circumstantial, but the only thing I should have done differently was disconnect the battery before I removed the seats/undid the yellow SRS connectors in the seats.

It's behaving exactly like an AM2, which I've dealt with and keeps skewing my mindset. Maybe an immobilizer ECU failure?

Maybe I'm overthinking and it's just fuse 6 or 30 inside the cabin

 

None of the IGN or immobilizer fuses. Scratching my head here.

Battery is at 13.1V. Jumper cables from the other car are at 14.5V. No problems there.

I feel like I'm out of ideas. Would a disconnected/messed up SRS seat sensor cause a no-start?

 

I’m mostly just documenting my hell at this point.

It's acting like it doesn't recognize the fob. The buttons on the fob work to unlock the car. The dome light doesn't come on from proximity, the car throws the "No key" light unless the key is in the slot, but then it doesn't do anything.

This is with both key fobs.

It's as though the radio signal from button presses is no issue, but that the car detached itself from the RFID identifiers in the fobs.

How is this fixable? Doesn't Techstream need the car to be "On"?

 

So I have most of the answers together. Part of it is that I'm an idiot. Part is that the car has lost its mind.

Unrelated to anything, I replaced the key fob housings several months ago. I forgot to carry over the RFID chip into the new fobs; just moved the circuit boards. The car didn't care because the smart code doesn't rely on the RFID.

After the car battery had died because I left the hatch cracked open for days on end, I charged it back to life.

The Smart ECU seems to be malfunctioning. This only became a notable problem after the repairs that didn't touch it. I tried replacing the RFID chips in the key fobs to no avail; I finally had a locksmith come make the repair and he was able to program a brand new fob to the car, but only through the slot. The remote functions don't work at all. The smart proximity functions don't work at all.

So technically I can use the car again, but the Smart ECU doesn't want to connect to any keys at all, and remote programming doesn't work.

 

The LEDs work. The locksmith did all-keys-lost, so my general understanding is that the two originals will not be able to function anymore?

 

That ECU communicates to Techstream just fine, strangely enough

 

There are codes; I'll have to pull up Techstream again when I'm home to verify, but they were in relation to the Immobilizer and Smart ECU not communicating.

I can see the Smart ECU when the car is off or on (it turns on now post-locksmith, but with no Smart or remote function).

All fuses are fine.

I'm losing my mind.