Hi, I'm having the same issue. Recently, bought RE200/AC750 Wi-Fi Range Extender and all set up and it was working all my devices. 1 month later now and stopped working all of a sudden. Now, there is no way to reset and can't see its default or new SSID in Wi-Fi list so, impossible to start from scratch for setup. I've pressed reset button but nothing is happening. 

Plus, tried to connect via 3 different Ethernet cable, 192.168.0.254, this is also failed... there is no way to enter device

I've hard reset my Internet Modem, changed the modem's SSID and Password but that does not help.

When I plugged in the device to the socket,

- First all button goes to green

- then less then a second, Wi-Fi LED goes to Red and all other still green

- then all goes off but only Power LED is on, as solid.

Could you please help me in here on urgent basis?

If needed, I can send you a video

Details

Model: RE200 (UK)

Ver: 5.0

S/N: 2232145001057

MAC: 48-22-54-98-86-76