Maazter

Hi community, I have recently had my turbo changed by a mechanic, after this change the ignition does not function as it once did, normally the ignition used to be a kind of trip switch, so it just needed a quick millisecond turn and the engine was turned on, Now I have to hold the key on until the engine turns on. My question is... What can he have done that would make this happen? he says that he never touched anything of the ignition or electrics! Car specs.. A6 2010 C6 120 kw 163 hp Estate(Avante) left hand drive. in Belgium Thnx in advance of any answers.