If you have similar question, please read this thread.
It's the third uni s mod that I bought because I've had issues with the first two and now this one I just bought a month ago and I got the same issue with it. I put the cartridge in there after the magnets put on it and it blinks five times. Now it says it means no atomizer but there's clearly one in there because I put it in. It's the same thing that happened to the first two so I don't know how to fix it I just went ahead and bought another one and now the same thing happened to this one.
I think due to the incorrect connection, the UNI S battery wont detect the vape cartridge.
Learn more detail refer to the Yocan UNI S user manual page.
Please try to use a q-tip to clean the contact points of the vape battery chamber.
By the way, did you try to install the same vape cartridge with the new UNI S and the older device?