My phone charger broke, so I had been relying on a usb cord plugged into my mac with the ends chopped off to charge my phone. It all went fine until a message saying: USB Over Current Notice: A USB device is currently drawing too much power. The hub that it is attached to will be deactivated. I unplugged the USB, & tried to exit the window. But my mouse & keyboard, (anything plugged into a USB port wasn't working.) I need to fix this, but I can't reset the PRAM without a keyboard or mouse. Please help.