Diagnosing a leaky metal roof
If the roof is faded this tells it is older and the rubber seals on the fasteners may be failing. This has happened on my barn and I start replacing all the screws with new ones. With a thermal camera you may be able to identify the area that is leaking from inside. I would just replace the screws or find new seals, I tried 1 time to replace the seals getting the old ones off was a total pain on many of the screws so I got new ones, and tossed the seals in a box.