My Genie garage door chain is broken. (There is a related issue at issue).
What I want is to connect two sections together via a rivet. But I don't know if the theory right?
Yes what you are looking for is a "Master Link" - they are available from places like Grainger, ACE hardware, Home Depot, Bicycle Shops, even amazon.
I looked at your pic - enlarged it - and noticed you had a Genie Pro - I did a search for the following. The prices though might break your candy machine money..so you will need to skip the soda and snickers bar for a day. Somewhere under $4.00 ..
Genie Pro Chain Master Link
Using a linker as suggested above will work fine, but they're quite tricky and you have to get the right size.
Another option is a chain tool
It will just pop out/in the rivet. You'll be able to just remove the bad link and join the chain back up. [
It's quicker and easier to use and covers you for future repairs. You should be able to get one in any bike shop.
Garage door chains look just like bicycle chain. So I would expect that you could use connection links and splice blocks that look like those used for bicycles.