USB devices of that kind normally have some overvoltage protection, as the USB 5V power supplies might also fail and deliver more than 5V, but maximum 500mA, usually.
This is done by a power zener diode (>5V6, or so), directly between GND/Vcc, near the USB connector.
This seems to be the melf diode D15.
The 12V overvoltage has overheated this diode, as no fuse is available, and the 500mA definitely will be exceeded, so the diodes internal Si crystal has melted and might have built a short afterwards.
If you own a DMM, set it to diode test, and check if the diode shows a normal behaviour, or if it is low ohm in both directions.
In latter case, the diode might be desoldered and afterwards replaced by a new one.
The rest of the circuitry obviously has survived, because several switch mode power supplies can be identified on the top left, which normally beware the circuitry of overvoltage intrinsically.
P.S.: FB7 is simply a ferrite bead for supressing external noise, not a fuse, and will probably not short anything.
Frank