That's means it's hung, which it can do if something isn't correct like missing the flsh.hex or the USB drive isn't detected to prevent a brick. It can also happen randomly. Just hold the power button until it powers down and retry. Be sure your usb device shows up in videos, music, etc before trying the exploit
Thanks. Kinda disappointing, since I read the instructions thoroughly. USB is FAT 32, rightmost USB port, detected by the XMB, hex file is on root of USB, and the hex file has the correct MD5...