Beagle Bone Black USB current draw damage
Beaglebone Black has a power regulator module. Beaglebone black schematic Rev C has power regulator IC (PMIC) part number TPS65217C. Attach is an excerpt from the schematic. 



It is also highly unlikely that your USB host is damage. Attach is an excerpt from the schematic for the USB Host. There is sufficient protection.



I also suggest that you invest in a Serial Debugging Cable



This will enable you to monitor the boot process and determine the failure point.

References: 


BeagleBone Black Schematic
BeagleBone Black Accessories
BeagleBone Black reboots periodically
TPS65217 Power Management IC (PMIC) 
Can not boot BeagleBone Black with 4D LCD touch screen using pre-built Android images