As the title states. No lights on dash, won't jump start, no headlights, nothing. Replaced the battery and still nothing. Have 13v through what I believe is the BCM fuse back by the battey and 13v at the jump starting post in the front. Don't appear to have power to any of the fuses in the panel under the hood. Is there a main fuse that I am missing? Thanks in advance for any advice.

 

Welcome to the site. Check the battery cable clamps they have been known to crack.
tighten the 4 , 7 mm bolts in the under hood fuse box, beyond the clicks , gorilla tight!

 

Tightened the 4 7mm bolts to gorilla tight with a 1/4" ratchet. Do those hold the cables underneath? I haven't found power at any of the fuses in the panel and the smaller screw up above only reads between 1 and 3 volts. Still nothing.

 

The one with 12V on the lower left corner is the battery positive cable from the battery, the other on the upper left is the electric power steering cable. Did you inspect the battery cables in the spare tire well.

 

They look fine. I assumed (we all know what that does) that if I had good power and ground at the jumping posts, that the cables would be fine.

 

The small screw has 1v-3v. Did you hook up jumper cables to that?

 

I did not. Should I put a jumper wire there? Just to get it 12v and see what happens? I haven't found a good schematic so TBH I don't know what it is supposed to do, other than I'm assuming that it should have full battery voltage.

 

Welcome
Maybe you could post the year and model on your HHR. That way someone can give you the correct schematic.

 

No, don't put a jumper wire there. Like Oldblue said, that is for the power steering. If you had jumpstarted from that point, it could have fried the fuse block, which could explain the issues you're experiencing.

 

I will assume that you cleaned those 2 connections at the fuse block ? If not, and you want to, only do that if you disconnect the battery negative cable. Don’t want to have any shorts.

Next. I would check the main ground cable to the fuse box. It connects by the left front shock tower.