Did you ever get your 990 upgrade to work? I'm having the exact same failure as you. Nothing quite like owning a $1000 paperweight. By the way, the cable name for the serial interface is a RS232 Serial Communications cable. Radio Shack does sell them. Just make sure it's not the Null Modem version. Also, check to make sure that the gender is correct on both ends of the cable. I'll try the serial port tomorrow but I have to borrow a cable from work. I also have a call into support.