25' is bordering on long for a cheap HDMI cable and could be your problem. Perhaps you could borrow a short cable and move the projector to troubleshoot.
Digital snow is odd, but I'd start there. If a short cable gets you signal, then you know it's the cable. If it doesn't, then you will want to try to borrow a source to see if it's the Marantz or bring the Marantz to a friend's house to test the HDMI on a different display...