If nothing has been delivered
Once the line is late, Cancel & refund appears on it and you can cancel it yourself. The money is in your wallet immediately and the seller is not involved in the decision.
If something was delivered but does not work
Use Report a problem on the order. That opens a case which CubieMart decides, not the seller. A seller who never replies does not block it — the case stays open and our team can rule on it.
Add anything the case is missing as a reply: a clearer screenshot, the exact error text, what you have already tried.
Reporting a problem is not rude and does not cost you anything. It is the recorded route, and the record is what protects you.