I have read two of the reviews and I think I have a reason for the loss of light.  My son had no problems with the light up shoes, ever.  Then one day, in Orlando Florida, we had some pretty nasty weather and he got the shoes wet.  Well within a few weeks, the left shoe stopped working...We have never had this issue before.  Shoes we had bought three years ago, he grew out of them, still to this day work(saving them in case we know someone who could use them).  I am so very sorry for the other customers experience of the performance of their purchase and knowing how much shoes are for a growing boy, maybe this information on our experience might help.