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You should NEVER close a case until you have item or refund because you can't open a second dispute for the same reason.
You are only allowed 1 dispute per transaction so the only way you can get a second dispute opened is to contact Paypal (when and if you can) and see if they will open a second dispute for you.
They may decline citing policies but if you say you made a mistake then they might open a second dispute for you.
If not then if you funded your paypal payment via a credit card then consider contacting your card issuer and see if they will help you with a chargeback?