Halfbar

Hi, I am new to this forum. I recently swapped the OE head unit in my 99 4 RUNNER for an aftermarket stereo. I have done this many times on other vehicles and no problems. After the install the new head unit worked fine. 2 weeks later it has just stopped receiving power. I have checked all fuses and they are all fine, I still have power in my clock, cigarette lighter and the dome light. In fact everything in the truck works as required. I swapped the new head unit for the original OE unit and this is receiving no power either (thus i have ruled out head unit failure).When i installed the new unit i simply bi passed the amplifier behind the console. Does anybody know if there is an inline fuse solely for the radio or are my fears correct and does this point to melted cables ??