This.
If you do anything else, other than informing the authorities, you are knowingly using stolen property, and the excuse of "oh but i got it off some random guy on ebay (who has since disappeared) if/when the law comes after you isn't going to cut it.
The sooner you report this, the more likely you'll get a better outcome.
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You know that knowingly buying and trading in stolen goods is a crime right?
Well, even unknowingly doing it is an offence, but if you know about it and do nothing you really have no leg to stand on.
Laymans explanation:
https://www.gobankingrates.com/personal-finance/why-purchasing-stolen-goods-thief/
edit:
Also...
https://en.wikipedia.org/wiki/Possession_of_stolen_goods
Given that you have publicly announced that you know/suspect that the goods are stolen (and the laptop itself indicates as such - i.e., corporate ownership via MDM - when you try to use it), i'd be calling the cops to report it. Pronto.
Receiving stolen goods may be a felony in your state.