96 TL wont start... wtf

my buddys got a 96 TL. he replaced his stock radio and then two days later the car stopped running. it does nothing when he turns the key over. the lights come on so we know the batterys isnt dead. we took the starter up to napa and they tested it and said its fine. so now im thinkin its the starter relay or something. we checked the fuses too. but i dont know where the relay is on his car. any insight or tips on what the problem is would be grately appreciated. thanks in advance guys

hey did u check the fuse of the car
u'd better check all the fuses
hope u find it

Thats Fucked Up I Just Id Thte Same Shit I Dont Understan Wtf Is Going On I Pulled My Radio Out To Replace But Didnt I Put It Back It And Reconnet The Battery But Nothing Happend The Dealer Is Fucking Dumb Dont Know Wut To Do I Dont Think Is A Relay Unless Is Hiddin I Check All The Current On Them They Were Good ?????? Have You Fixed It Yet I Think Maybe The Starter Cilinoid Went Out Or Somthing Write Back