Here is a question from one Yocan fan.
Hi I bought 2 uni vapes 6 months ago and they both stopped working about the same time. I can hit them once after a full change. Then the 3 lights flash green and doesn't hit. Is there something I can do or can I get replacements for them? Thank you

Yes, the flashing 3 times error means your battery occur short circuit.
Here is some tips for your reference.
1, Re-install all of your UNI parts, include adapter, cartridge.

2, If you have a brand new 510 cartridge, please try to use this new one.

3, Or you have to contact the shop you bought it from.