Right at the 30 second mark, where your index finger is. That bolt looking stud sticking straight up beside the fuse box. That is the main feed from the battery to the fuse box.

 

The 2 things that you seem the most worried about are supposed to be loose. the wiring harness (the gray thing) comes from the factory taped to the other harness, but the tape breaks.

The big black box that you probably think is the battery is in fact the UNDER HOOD FUSE BOX. The top comes off to reveal the fuses and relays. There are 2 or three bolts that probably are loose holding the 2 halves together.

Also the big wire that attaches to the front most part of that box needs to be tight. The rear most wire goes to the power steering motor.

https://www.chevyhhr.net/forums/gene...al-3074/page7/. Use the link in post #63.

But the links in the OP are now fixed. Thanks for the heads up.

 

Believe it or not, I checked my cables in the REAR of my HHR for grins a little while ago, due to a sputter on start-up, and found that my positive cable was loose off the battery. Tightened it down, good to go since.

It does sound like voltage, and you really need to check ALL the power connections, fuse box studs, and under hood connections.