I have multiple door sensors within my Aqara app. I tried removing 2 of them so i could bind them via zigbee and HomeAssistant.
The pairing process does not work for both sensors. I tried pressing +5s during that process the blue led blinks rapidly,'until I release the button. Then no blue led anymore. I tried mairing via zigbee ( not discovered ) then again via the Aqara app and my E1 hub . The sensors are not discovered
Don’t know what to try next?
Had the same issue 
After removing from Aqara the sensors do not fully reset and would not re pair.What worked for me was holding the button 10–15s until multiple blinks then retry pairing immediately.
Tried that but a very long press doesn’t do anything for me
Do the sensor needs to be besides the magnet for pairing?
I now remove the batteries from the 2 sensors. Wil try again Tomorrow …
Don’t know what else to try
I had the same issue recently. The solution was to turn OFF the „accidental removal protection” in the hub settings.
Hello, I confirm this. I also encountered this problem. I deleted the T2 relay from the application and was able to add it again only after disabling the “prohibit deletion” function.
Well that setting is off , so not the case with my door sensors. I never seem to get them into pairing mode ( manual says 3 times blink ). As soon as a let go the reset button, the blinking stops… also after removing the battery for a long time
Do you have another phone, try it with it?
If that doesn’t work, contact Aqara support.
Yes ipad is the same issue
Also only 2.4Ghz wifi is active now, still no luck
Contacted support…
Please note that there may be weekends and holidays (I’m talking about the support service).
I recently reconnected all my sensors. I had some difficulty putting one of them into pairing mode. I removed the sensor to make the button easier to reach, as I had always felt that I wasn’t pressing it properly. Even then, it was difficult. If I recall correctly, the LED also flashed three times and then stopped when I released the button. Next time, I held the button down for longer. I believe I held it down until the LED started flashing continuously rather than just three times. Then it worked after a few tries.
Alternatively, you can set the device to factory mode. Press the reset button quickly 10 times and the device will reset to factory settings and the LED will start flashing.
Unfortunately they both won’t go to factory settings it seems ( by pressing quickly 10 times ).
No 3 times led afterwards
I have other door sensors actove,and i’am
Afraid that if i remove them also from the aqara app ( to re-add them later via zigbee or again an aqara hub ) they will fail also
I think the 10 times pressing,is for the newer door sensors. Mine are a bit older, I guess 3 Years now. Maybe 4 
And also do the magnet needs to be besides it when resetting, that’s another question. Because off course the magnets are attached to doors and windows now, and I have taken the sensor of the doors to reset etc . Don’t know if that makes a difference or not ( I tried ayways pairing them wgen attached, and it didn’t work )
Sorry, it was already late. I checked the P2 window/door contacts, which can be factory reset. You should have the T1 contacts for windows and doors, just like me.
No, the magnet is definitely not needed. I installed my contacts at the top of two-metre-high windows so that they would also detect tilting. In order to change the battery or reset them, I have to remove them, which is why they have this click function that the magnets don’t have.
Also, it’s important to note that there are…
…in the app!
I had always selected “Door and Window Sensor” and it didn’t work, but when I selected “Door and Window Sensor T1”, it worked!
I just checked and ordered them in 2020 it seems. SO that should be the normal ones in the app( without T1/P1 ). But anyway I have no luck with both of them. I do this with the E1 hub, also in the back there is the round hub with speaker… Maybe I’ll try with that one, but shouldn’t make a difference ( the door sensors all paired with the E1 )
Okay. Have you tried it with new batteries?
not yet will need to check if I have lying arround. Definitely will not try take them out of a working sensor
Freshly purchased ones that haven’t been stored for too long are best.
There is usually a use-by/best-before date on the packaging.
they are hard to come by it seems in stores here, so I just ordered some online. Need to wait a few days… in the meanwhile maybe aqara support will contact me anyways thanks. If all fails I just order 2 new sensors. They are not that expensive
LOL . I just fearless did take the battery of another working sensor and put it in the non working ones… as soon as I pressed the reset button ( it started blinking as before ) then released it after 5 secs ( the 3 leds did not come on with the old battery , but now it does with the batt of the other working sensor ). Paired them again… and re add them fine. Put the old battery in the working sensor, and works also… So I guess its time to replace some batteries haha