If pressing the power button does not appear to turn the device on check the battery then check the screen and keypad.
See the section “battery won’t charge” to test or replace the battery.
If the keypad lights up when you start the phone but the screen does not light up the screen is probably faulty.
This issue may be due to a faulty battery or a faulty charger.
See Sony Ericsson W518a Battery Replacement.
If the screen was determined to be faulty in the above replace the screen with on taken from another Sony Ericsson W518a.
If the keys do not work replace the keypad with one from another Sony Ericsson W518a.
see Sony Ericsson W518a The keypad Replacement.
see Sony Ericsson W518a Camera Lens Replacement.
Clean the inside and outside of the lens with a microfiber cloth.
If the cleaning the lens does not resolve the issue, try replacing it with one that was taken from another Sony Ericsson W518a.
If you need to transfer the SIM card and install a new SIM card into the phone see Sony Ericsson W518a SIM Card Replacement.
If you want to replace the faceplate or install a new one see Sony Ericsson W518a Faceplate Replacement.