Yes, there is. Theres a magnet system and a light. The light comes on when its open.
He said to me, he wired a relay to the light output. Thank you Vincent youve been a big help 
That’s why, it’s fried. It was the light output. We can still use it but you will NEED a multimeter and a relay.
He said there was a relay on it… there should be no voltage. Anyway ill get a multimeter and check
Hi Vincent, I spoke to the gate guy. What he has done is placed a relay inside the gate motor, the input into the relay is the output from the Light (24Volts) the output from the relay is 100% voltage free. I will get a Multimeter today and confrim this and take a photo of inside of the motor.
He says theres no way we could have fried the Sonoff using those two wires.
Ill report back with a photo and multimeter results
EDIT: I have a Multimeter in hand now
Hi Vincent, ive got my Multi. Set the Meter like this… red terminal on one wire and the black on the other. I get 0.
When triggering the door I still get 0
Set the multimeter on the circle with 4 small symbols to test continuity. then trigger the door.
And then can you show me the wiring of the relay in detail, please? And tell me which wire is which.
The two wires to the sonoff are on either side of the relay. The light input are the two wires on the right (bottom)
Multimeter says ol when triggered. Relay has a red light on when the door is open
With the Door closed. The resistance appears to be about 0.7. When the door is open it shows OL (0.L)
Ok, so we have continuity when the door triggers.
The sonoff, I think is configured properly to detect changes as a switch on GPIO2 and doesn’t react for some reason.
1.5? that’s not good. the resistance should be infinite
I need a really good close up of the relay. I think the output wires (The ones that should go to the sonoff) are wired to the wrong terminals on the relay.
But even then that will not help if we can’t get the sonoff to react to a change of GPIO2
I’ll have to think of something else and maybe I will need remote access again to speed things up a bit
Ill send you the password again and get a good photo of the relay.
Thank you Vincent for your help!
In the end, we rewired the Relay in my gate motor and setup a new topic in Tasmota. We connected GPIO2 in Tasmota to the Gate motor and defined a text item in Sitemap , along with a Contact item.
All works nicely!