Recently bought a 2009 Pontiac g3 it was running great then it let me sit the ignition relay switch blew put another one in and it ran for a day then quit on me again i took it to a shop they had to replace a wire with a fusable link that bill was over 500$ they said they couldnt find anything wrong except that and that it is unfixable wich i think is a crock they just didnt want to look for the real problem so now im guessing some wire is shorting out some were and is causing it to keep blowing. Or is there somthing else im missing? If thats the problem what would be the quickest way to find the bad wire??

Thanks for your help!