SC400 radio problems
 

Hi everyone, I own a 1994 sc400 it's my first car i am currently 17 and have been driving it for about four months what an amazing car feels like a 2014 and its a 94 lol. but I've had really crazy issues with my stereo system, it worked perfectly for about two and a half months and then it wouldn't allow me to power the radio on a cold start. then it decided that it wasn't going to turn on unless it felt like 1000 degrees in my car, recently within the last three weeks it has just stopped turning on completely. anyway, two questions: Does anyone have any idea whats going on? and if I get an aftermarket radio how do I make it work with the power antenna? thank you guys so much for all the help, these forums are the best thing and the community is just completely amazing.