If a TRIAC or IGBT is in good working condition, when you test continuity between any of the terminals, there will not be continuity because the Switch (TRIAC or IGBT) is OFF.
For the TRIAC, connect the positive terminal with the DMM in the 200 Ohm range at the A1, negative to A2.
There should be no indication
Now connect GATE with A1 and you should see some indication.
Disconnect the connection between A1 and Gate and the indication should change slightly.
Disconnecting momentary positive to A1 and reconnecting it you must have no indication.