Fitting a new mirror casing with indicator on a Sprinter 313 cdi

Hi, I had both my mirrors and casings smashed on my Sprinter 313 cdi, I've bought the whole unit as in black plastic casing, mirror and indicator and took the old plastic casing off by removing 3 x screws on the inside of the door it's is now hanging by the indicator wire through the door frame, I've taken the rubber tube from the door to the door frame off and can see a black insulated wire that looks like the indicator wire going into the engine area, I've opened the bonnet and can see a rubber conical shaped tube with a bunch of taped up wires coming and a plastic tie round it which I've cut off but cant see how to get the rubber conical tube off that's covering the wires as it seems to go behind the metal bodywork, how do I get to the connector from the indicator light to change it?

Will I need to unravel all the tape round the wires coming into the engine bay to get to the connector?

Hope this makes some sense to someone?

Thanks