can I blow the ECU or onboard computer by reconnecting...

[omodos]

can I blow the ECU or onboard computer by repairing.......... the severed green/blue wire that runs into to the webasto auxillary unit shown in pics below?I saw the wire was was cut and the mechanic told me that it may have been cut for a reason and if I re-connect it I may blow the ECU or damage the OBC! the wire runs to the blue green connector and from there runs into the center of the webasto unit and the wire has a label on it saying 'feel the drive' ,the car reports no issues, and to be honest I never have used the auxillary vent or heater to see if it works (ambient temps here are in the 80's)although I do not think I have the actual heat option as I do not have the key for it. Would really appreciate anyones advice on this before I get the wire re-connected, can it really do serious damage?