Aha!
Shorting does NOT do it, so that's not going to work for me. Thanks.
so you have a flood of suggestions for different relays....but none of these will work if the circuit does nothing! The Insteon device you're replacing is just a relay so if it ever worked we can be confident you have a new and different problem given shorting the circuit is all any relay will do (Taswe's posted wiring diagram also confirms that you should be closing an open circuit).
(Conceivably, you were using the 8-channel relay perfectly after all, the Insteon never failed, and you may even be competent in mqtt without realising!!!)
if you are 100% sure you're wired to the correct terminals, and nothing else has changed since removing the Insteon (eg mixing the door sensor inputs with the relay outputs), try running a new cable. Also, if you're piggy-backing a physical switch circuit that is using the same terminals, remember you need to be wiring in parallel, not adding the relay in series (or neither will work unless they're both activated simultaneously).