Starter relay issues

(These) and many other relays are dead nuts simple. In this case 4 terminals

The two "push on" flag terminals are actually interchangeable. They are the magnetic coil. The it works.....The yellow "start" wire comes from the key and is "hot" when twisted to "start." In order to energize the coil (magnet) the ground must be "made" by the transmission neutral safety switch in P or N

Now the contacts are sucked closed, "the switch" is "made."

The switch, or power section, is the "big stud" and the "big square" screw. The big stud is one contact, and also serves as a junction point.

The "square" screw has a fairly large wire that goes to the solenoid terminal on the starter. So when the magnet is "made" the contacts close, sending battery power from the "big stud" down to the starter

With Chineseoationized parts nowadays, not surprized you might have gotten a bad one. It's also possible (but should not be) that you overtightened the terminals and moved the contacts out of alignment.

Personally, if you cannot return it "as defective" I would bend the tabs open and see what's wrong in there. You might be able to fix it