OK, then it's ambiguous at best.

The way I read it, I took it to mean that if a device arrived faulty from the factory it would be replaced, but since Quim doesn't go on to say what would happen to those devices that subsequently develop a fault after one week - and because I don't think Quim would want to leave us in the lurch - I'm willing to believe it is just a poorly worded sentence and I can accept your interpretation.

A rewording from Quim would put my mind to rest though.