Get the torch out !!
It sounds as though you've disturbed a connector coming from the power supply. Be care and pull them out by the hard bit and not the cable. Push gently but firmly in and then listen for the one single bleep from the speaker.
The ESC is quite a simple MB and quite well made, just removing a line of memory should have no bad effects.
Its not unusual to find that although a plug is 'home', just one little piece of cable has detached itself from the connector.