try:
dev = putusb.NvidiaUsb()
except putusb.NoDev:
sys.stderr.write("No tegra device detected. Check device ownership and
sys.stderr.write("No tegra device detected. Check device ownership and cable\n")
cable\n")
sys.exit(1)
dev.boot("bin/tegra_pre_boot.bin", "bin/fastboot.stock.bin")