is it possible that the Kit Nike Ipod has sensor and connector with two different serial numbers?, is it possible that the Kit Nike Ipod has sensor and connector with two different serial numbers?

Good morning,

I resold an unopened Nike + Ipod kit.

The buyer told me it was not working and sent it back to me.

Upon return I found that the sensor had a different serial number from the connector (the connector serial matches the on on the box, the sensor not).

Before taking legal action, I would like to know some things, being not an expert:

May the connector and sensor have different serial numbers?

May be that the box was opened by someone before who replaced the sensor before i bought it, or I would have noticed as the box has some security features to prevent such a thing to happen? (like broken seals, or it breaks noticably)

Is it possible to test the sensosr without taking the connector out of the box?

Thank you

izziomelis