Yeelight ceiling light doesnt work out of the box

Today I had my two ykxd50yl ceiling lights installed. One works fine. The other cannot be turned on and doesn’t show on Wifi neither. When I turn the physical switch on there is a small flash of light. I have tested the electricity and wires, everything seems to be fine. Is there any hope? Is there something I can try or I just have to send it back?

Thanks for your help.