i was there too! it was amazing!
actually one of my friend's xyloband also didn't work, but he finally got a replacement his xyloband with the working one from a staff on the gate, and the staff didn't ask for the broken one so he got two xylobands.
and a random guy next to me also had a broken xyloband and i told him that he could change his xyloband at the gate and he got the working one :D