Was the ext usb device from a name brand company? i have seen many cheap imported usb devices that can cause damage to a computers usb port
usb ports on most computers are not very well protected, and can be damaged from a badly designed device, or normal static electrictry. ususally this just blows the port or the port and the usb hub but leaves the rest of the system ok.
Your AIO's power supply could have failed. if you are unable to test yourself, have a alocal repair shop do the test.
do not ask me how to test, as if you do not do it right, you run the risk of actually causing more damage to the supply/system because a AIO's power supply is not made like a normal ATX modular supply the display is powered off the AIO supply besides all internal devices MB/HD, and so on and in a AIO each device can have it's own sub power system