If you had used the Ebay Money Back Guarantee and returned the phone through a 'not as described' case, you would probably have had fewer issues.
There is no need for the seller to state they accept returns or believe what you tell them, Ebay would have supported your return and ensured a refund.
If Paypal had decided not to refund, you wouldn't have subsequently been able to open a return through Ebay.
Always go via Ebay first.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)