And if all fails, Don't Accept any responsibility for an Electronic fault that may have happened due to you "HAVING" to disconnect the battery, He brought the Car to you, ( It could have gone anywhere, but you got lumbered with the French pile of Crap ) If a fault occurs due to disconnecting a battery, it isn't your problem, These things happen Occasionally and you should not be held responsible, If you had Blown something by connecting the battery the wrong way Or Shorted something out due to not disconnecting the battery when you should have done then You are responsible and should be prepared to cover all costs, But Not on this occasion.