Battery in Trunk wiring completed, now no power at all

crackedback said

Everything inside the car is pretty much fed from the alternator black wire running to the ammeter.

If the red and back ammeter wires are not connected, it won't power up the fuse box, headlights, etc.

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So, even though I have power at both sides of the ammeter, just not connected to the alternator, it could cause this problem? I would think if it has power on both sides it would be feeding the black wire where it splits off from the "welded splice" to power the car and other things.