One of the issues here is that you probably don't know what is wrong with the console (if anything) since you got it of ebay unless the seller could tell you. Was it supposed to be working? I would of course double check your newly soldered connection. Not that I doubt that you do a great job, but it does pay off to double check ones word. You did say you have the correct pinout. Do you have the schematic for the Saturn? If you do, you are a huge step ahead. I would start with checking the output of the power supply. If my notepad serves me right, on the power supply are 5 pins that connect to the main board. 9 volts, 5 volts, 3 volts and 2 pins for ground. Check those and see if you have power to the whole console. Number one concern must be to get a display that is working. check the power supply fuse and take a look inside the PSU just to make sure that your caps are not leaking etc.Also check your boards for any burnt out components, I know that the Saturn has issues with Varistors and fuses. Go from there and see what it does. Let us know so we can continue to assist you.