Sounds like the bending has caused damage to the insulation of the wires inside the cable and these are shorting out and causing the overcurrent.
If you can solder you could cut the plug off with a couple of inches of cable and solder a new plug on,or even replace the whole cable.
If its a cheap keyboard then the best option would be a new keyboard.
A temporary solution may be to straighten the cable out where it enters the plug and then wrap insulating tape around the cable and plug to stiffen the cable and keep it straight.