Tim managed to create a time machine in secret. Foolishly, he used it on himself, like all good (movie) scientists do and traveled back in time. He thought he configured the machine to five minutes, but he instead accidentally sent himself back to medieval times, where he was promptly killed for witch craft.
Many years later, archaeologists/scientists are baffled to find a corpse from seemingly medieval times wearing modern clothing and gadgets.
Conspiracy theorists are already shouting "time traveler!", but the scientists try to come up with a more reasonable explanation, as they know time travel isn't possible, obviously. They're trying to think of ways of how a modern human could've suffered decay that made him seem like he came from medieval times.
What would the scientists come up with? Or would they realize the human remains actually were from a time traveler?
Bonus question: they find a smartphone on the corpse, but it's the 90s and smartphones weren't invented yet. Over the years, would it suffer enough decay to make it unrecognizable?