Just got a pre-owned HTC Desire 500. After resetting I connected it to my PC and found the phone storage almost full. I deleted what I could but it is still full, I displayed the hidden files but but still its not them filling it. Also in "settings> storage" its weird it says there's 4gb of storage and 2.94 is occupied by other files. Please somebody help, I can't update built-in apps like facebook because there's insufficient space.