I attempted to bring up my lock screen so I could check my e-mail, yet it doesn't come it. I tried the sleep/wake button and the home button, yet nothing works. So, I thought it might be dead despite charing it last night. I plug it into the charger... nothing! It doesn't even make the sound that it is charging. I plug it into my Mac, doesn't register. Any ideas what could be wrong? It's the CDMA iPhone 4.