Contact valve and see if they can lock it somehow. Since it should be tied to your account in some fashion. You might have an uphill battle proving it was stolen , but then again was there a bill of sale because of not then the entire transaction is here say… you probably won’t have an issue proving that you don’t have access to YOUR steam deck ;)

Verify the property is not reported stolen .

When you sell that item to a pawn shop the first thing they do is check the serial number to verify it isn’t in some registry for stolen property.

In most states receiving stolen property , even unknowingly, Carrie’s a pretty steep fine / jail sentence and will live on your criminal record. Hard thing to explain away even if you do everything right.