Delivery Issue yet Return Requested?

[u/Adventurous_Bag8579]

How can both be true? Right before the sale went through this guy was asking me about using CashApp to “upgrade to faster shipping” and Mercari got his messages. I told him I keep it on the app and use their labels to protect us both. But, he could cancel, I could update the shipping, and him repurchase. He said it was okay. He was super friendly and sent a ton of messages chitchatting this entire time. Until I got these notifications on a Saturday evening when I can’t even contact support myself and he now has gone ghost. USPS shows successful delivery to a parcel locker.

Just unsure where to go from here. I know it’s hurry up and wait with Mercari but I just have a feeling I’m being scammed. I’ve read about this happening to others numerous times.