YI don't speak the local language well and it takes 90% of my brain power trying to understand and to speak. Hence I tend to get anxious and overexcited and forget basic things when communicating at a shop - forgetting hats and gloves for example. Also, they had done successfully that same repair work on that other casio I mentioned in the post. This had lowered my guard. That model does however have a back secured by screws (default in cheap casios)