I can't update or downgrade my iPhone 3GS, Firmware 4.3.5 tethered with redsn0w. Whenever I try to update it, I get a "device isn't eligible" error. I researched on how to do that, like changing host files, but none of them worked for me. I use OS X Snow Leopard. ## # Host Database # # localhost is used to configure the loopback interface # when…