Controller problems - Help

Hey, just wondering is there someone that can help me out with this one. Have a PS3 with two wireless controllers, one is official sony and the other a cheaper knock off version. The sony one just randomly stopped working last week. Wouldn't charge or turn on or anything, just nothing out of it. The other one still works fine which led me to believe the sony one was broken. The little brother can get a little angry playing fifa at times and I fear he may have slapped the thing against his chair a few too many times.
So I went into cex in dublin city centre and picked up another sony controller for 45 quid. Got home and its the exact same story. Absolutely nothing out of it. No charge or lights on at all. There is a chance I was sold a dodgy controller but I know cex generally test their stuff pretty well before selling. Just wondering is there maybe some sort of settings that could have been accidentally changed to cause this or something?
Any help appreciated.