Garmin S2 wild body fat reading

I have just received my Garmin S2 index scale and I am puzzled.

Previous reading of my body fat percentage indicated approx 18-19% and my physique is pretty much the same.

The scale on first weight-in indicated that apparently my body fat percentage is now 30%…. the numbers don’t even make sense.

Shall I just return the product or can this be fixed? 
A 10% discrepancy makes the product quite useless if persistent.

shame as I was a hard-core brand loyalist