Ordered a laptop and didn't arrive?

I ordered a laptop. A neighbor thinks he saw that the parcel was in the stairwell (from a large apartment building, the door of which is always open due to an error). But it is not there (anymore). Who is liable? Can't the Hersheller somehow track that when someone logs in?

https://www.bezahlen.net/ratgeber/gekaufte-ware-kommt-nicht-an/

No, the parcel service is liable because they put it that way

DHL is liable.

If it was a parcel then nobody is liable without insurance.

If it was a package, there's liability as follows:

If the messenger simply left it there, then DHL.
If he has delivered it to a neighbor who has allowed it to be parked in the hallway, or has it parked there himself, then the neighbor.
If you have issued a parking permit and it was allowed to be parked there, then you.