It's been a long time since I updated my CS8k,so don't consider this carved in stone.
If I remember correctly,the 8000 firmware is different from the 8100,updates must be done via the serial port with a null cable (pretty sure but not positive on that).I have the pirate version on mine because that came out first and the factory firmware is just the pirate software with the pirate stuff removed.Towards the end the pirates were the only ones providing the support for Coolsat.
Anyway if you were trying to update with a straight serial cable try a null,if you were using a null try a straight,it really shouldn't take more than a minute or two to update.
And last you can't update via USB because the 8000 doesn't have a USB port,the USB on the 8100 is just for the DVR.