If you have already have it set to wake from USB mode, then you can check out this article on how to do a software reset.
I have an AltaLink C8070 with firmware version 103.003.032.2340. The device is configured with energy saver settings of "Job Activated", 30 minutes for Ready Mode to Sleep Mode and "USB Port State in Sleep Mode" is set to Powered. This configuration page clearly states that "the USB Port State in Sleep option allows USB ... and Card Reader activity to wake the device from Sleep Mode..." In my case a card authentication attempt to a USB Card Reader plugged into the Front USB port ( the USB Port Security setting is configured as Enabled ) will not wake up the device. If I press the power button on the display panel and wait for the device to wake up then usually the card reader will authenticate the user but occasionally will just beep and not authenticate. At this point I need to either unplug and re plugin the USB card reader or reboot the device to get it to authenticate a user again via the card reader. I've tried multiple card readers, same results. Does anyone know if there is another setting that I am missing somewhere or if this is a known bug?