Hi @Allan_DK , I have exactly the same problem.
Yesterday I received the lamp, after install it on the ceiling in my living room, it was working properly until I tried (following the APP recommendation) to upgrade firmware. Then, absolut darkness, no response to the switch on the wall, tried to reset with no success, tried to connect directly to a plug using a cable, still no success.
I also deleted it from the APP, but then no chance to add it again. Strangely , the AMAZON ALEXA APP could see/detect the Lamp, but also nothing happens. At that time I have the suspect that there were a WiFi problem.
After a while, I uninstall the APP on my iPhone, and tried to change the zone from Europe (I live in Barcelona) to China, and magically the Yeelight appears again on my APP. But still doesn’t work.
After some minutes, I tried to swith on/off several times, very fast, probably in 5 seconds, and then the YeeLight start working again, but no response from the APP.
When I turned off the light to go to sleep, the light never come back to life. I am trying the reset Swith On/off 2 seconds per each, 5 times in a row, with no success (probably I’ve tried more than 10 times). I also tried to switch on/off very fast, as yesterday, but nothing happens. The APP doesn’t detect nothing.
I have seen, searching the internet, that there is an APP for Android devices, that seems to bring back to life when there are connections issues, but I don’t have an Android phone, and due to CoronaVirus, I couldn’t go to my office to pick one device.
Honestly I don’t trust so much on Android method, because the light is absolutely off/dark, it doesn’t response to any kind of energy impulse.
So I assume I have a nice brick instead of a Lamp.
Any help from anybody will be really appreciate.
Best regards,
David, Barcelona