The unit was tested this afternoon. Unfortunately, the drive for was not sent in for the current draw testing. We may never know what role the device played in the USB port failure.
The USB IC is damaged and will not allow any drive to mount. There is no physical damage to the PCB or USB connector. The port is outputting normal voltage and current but did drop 20% under load. While we wouldn't expect to see this large of range, it should remain within typical USB device operational range. It is impossible to determine the cause of the IC chip failure.
As the microHD is under warranty, we have decided to replace the unit at no charge rather than take the additional time to replace the IC.
We recommend that if this portable drive is to be used again with the microHD, that it is only used with the USB pigtail and external power adapter.