Well the lock button is kinda difficult to use now, I at least have to push it 5 or 6 times or more to unlock my phone, should I go to a store and let them make it for me or can i do something my own?
I agree with @Thommo contact your local Sony Xperia Customer Care team to get this into an authorized repair agent to be fixed, they will bring the handset back to warranty condition for you and if it is the M4 Aqua they will ensure the water resistant nature is maintained for you. Keep in mind repairing the handset yourself may result in a voided warranty.
