Yesterday I found out that one of my H2 EU switches is unresponsive. I tried to restart my M3 hub several times, but with no luck. So I decided to reset the switch and pair it again. In every manual I found, it was written that I have to press 10 times any button. Well, this works apparently only if you have neutral wire connected.
So, if you’d like to reset your switch without neutral wire, you have to switch on and off the circuit breaker 10 times. At least, it helped me.
Resetting my H2 has been one of the worst pains of my whole home. I have 2 Aqara switches on Matter and they’re the thing that fails most on my whole network. 
I can’t even reset my H2 with neutral. The light remains solid green no matter what I do.
Thank you for sharing this. I’ve been struggling with this. I have a no neutral switch in the US that I had put in decoupled mode. While troubleshooting I deleted it from the Aqara app before disabling decoupled mode. This at least gives me a direction to go in.
Thanks.
I was able to reset my switch. I started by placing a piece of painter’s tape over the switch to hold down the button. Then I toggled the main power 10 times. After a few seconds, my switch started to blink. Hallelujah!