Ugh, sensors failing is such a headache! I've seen a bunch of posts about similar issues online. It might be because of firmware updates or just cheap parts. My friend's unit died after a power surge last year. He had to replace the whole system, which was a huge pain. We really need better quality control from manufacturers!

Check for any stamps or markings first thing, because that's how you catch most modern items (I've seen so many misses with this). Clean the object carefully with a soft brush to see hidden details, since dirt can hide obvious clues. Look at where it was dug up, too, since gardens and parks often have recent junk mixed in. I helped a friend realize her "ancient pottery shard" was just a broken coffee mug from the 80s by spotting a glaze pattern. It's easy to get caught up in the excitement, but a quick reality check saves everyone time. Always assume it's modern until you have solid proof otherwise.