head unit power problems

hello im kind of new to this stuff but i would like to do this my self. i bought a sony hu i wired everything correctly but when i plug it in it turned on for a bit then just stopped pretty much and my old radio wont work now either. what should i do about this should i just buy 1 at best buy on free install day and let them deal with it or should i try it myself i have all the parts and stuff but i dont no that much about all this stuff.

what kind of car are you wiring this in,    did you check all your fuses?2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

2007 USACI World Champion

2007 World Record

2006 USACI Finals 2nd Place

depending on car most cars have fuses under dash,on the side of glove box and even under hoodfor the most common locations other spots include behin ashtray under passanger seat or to make things simple just look in your owners manual if u have one.....AudioPro111