The 2 Pads in the middle are ground. This 2 pare are connected in the bottom pcb layer. I think you pcb is working, you have only connect the 2 Pins on the bottom layer.
Unfortunately the back ring is off too. I tried to solder it directly on the board but it won’t boot the fans.
What is the ring called? I’m think buying some online to replace them order to see if it will help
Back pic attached.