My friends Nexus 4 wont charge. He has used different chargers and made sure there is nothing in the phone charging port. We don't know how to take these phones apart so I cant get to the battery. What should he do?
When you plug in the charger to the phones Micro USB Port very carefully, slowly and very little push the charger that's plugged into the phone forward just ever so slightly and hold it and see if it begins charging, if nothing happens try the same thing but towards the back of the phone and hold it. If it began charging when you did this in either directionthen your phones Micro USB Port is damaged and will need to be fixed, as this is considered physical damage it's not covered under warranty and you will have to pay for the repair.
If nothing happened when you did the above then you might just be best to send it for repair or ditch the phone and take the chance to upgrade to the Nexus 5 which is a much better device in every single aspect and IMO one of the best devices of 2013 / 2014.