Dude forget eol
If you wired tamper and alarm , linking the zone clears the led as you say ,
Does it do that on a zone connected to a PIR?
If yes reconnect wires , join the alarm wires at the PIR , does it clear the led ? On setting
There's simple methodical approach to this
Just like you would fault find on electrics ? Unless your just first fix then I understand your current approach , (current unintended pun but I think I might use it again )