What went wrong?

I'm on a cut. Even bait looks tasty.

he didn't keep the bar over his heels

he wasn't trying to do a hack squat

center of mass over the heels isn't a backsquat thing, it's a balance thing.

You're fucking retarded. You can see the bar digging into his shoulders and collar bone. It made him dizzy on top of cleaning a good amount of weight for himself.

He shouldn't have leaned backwards, otherwise he could still have dropped the bar

know how I know you don't do weightlifting

centre of mass stays on midfoot, heels is retarded

The brain doesn't "shut down". Blood restricting results in lowered consciousness which signals muscles to relax causing you to drop so that your head levels with your heart and receives blood again. At no point does it go on "power saving mode".