Actually, we can't say anything. We don't have your car infront of us. Are the rest of your electronic instuments working, radio, dash, pw, lights and so on? I think it's the battery relay, but it could very well be an alternator problem or something else. There is something my friend did with my SC when i disconnected my HID relays. He hit the bottom part of the block--on the left side of the car. I think he called it "rocking" the block. Try hitting the bottom part of the block, just above the Pan with a stick end of a broom stick. It may do the trick. Don't forget to check those relays and tighten the screws.
If that doesn't work, you might need to tow it to Lexus.
good luck.