Document condition before sealing the parcel
Before packing, photograph the item from several sides and record details that may matter after delivery: finish, corners, displays, connectors, hardware, serial number and included accessories.
Document existing defects as well. The most useful evidence is not a dramatic photo, but a clear sequence showing the condition of the item before it entered the parcel.
Keep the original files at least until the transaction and any applicable dispute window for the service used have ended.