yes he can. but not too much- basically just negative feedback
Yes as it's a breach of sellers rules unless there is damage to the property and the buyer agrees to a cancel transaction case
You can cancel the transaction. Just put that in the inquiry field and follow the process to cancel. You wont get in trouble.
Most buyers will report you as a non-performing seller in a heartbeat. eBay will verify and if true, will kick you off of their site permanently. This is not a game.
Lie and tell him it broke
I sold an item but I changed my mind about it. The customer who bought it hasn't paid the money and I sent him a message telling him not to. Can he get me in trouble?