My jeep won’t start. I get into my jeep and press the start button and it makes one click and won’t start. All the accessories are on like screen and dash.

The brake peddle is very firm. The battery on my dash says it’s at 12v

I tried by unhooking the battery for 20 mins and same thing

I looked in my engine bay and this strap which looks to be a ground strap is not connected to anything?

any ideas what’s wrong?