Static / Hissing sound only from loud speaker on "System" sounds

Hi,

Bought an iPod Touch 4 on eBay to fix and only through the loud speaker there is a hissing / static sound when the device boots, is locked, receives an incoming call or on notifications. This doesn't happen through the headphones and music and keyboard clicks play fine through the loud speaker. I have restored the device 3 times with no success.

Another thing to note is that the backlight doesn't work (Due to the coil and IC I think) but I don't think its related as music and other sounds work.

Cheers.