Possibly starter wire, more likely they have damaged, or poorly fitted, the engine earth cable.
Do you have a set of jump leads? If so, take ONE lead, clip one end to your cars battery negative terminal and the other end to a solid piece of metal on the engine, something like the lifting out bracket.
If the car will now start, the earth cable is your problem.
Do not keep the car running with this jump lead in place as it may come loose, this is a test method, not a repair!
ben10, August 2009