same here. mine xperia p bottom cap is loose too. i tried pulling out the cap slowly n it opened. inserted two small pieces of paper at the both sides and closed it. it worked. now it quite tight.
But thats not the way. it should be well tight from before. what is wrong with """SONY""". All these problems???? sometimes its call lagging, sometimes phone hangs so bad that i wish to throw it far away. Couldnt make an emergency call due to its call lag and also sometimes cannot receive the call,, only keeps on vibrating, Please bring an effective update. if no, then stop bringing updates in phone which is further ruining the software. it was quite much better before updating my phone.
SONY ... keep the brand name alive.
