C4M5: how do I leave?

[Zillatron]

Hello, I need some help in this mission (this is the mission about blowing up the sub and then leave with a stolen vehicle).

I have blown up the sub, but now I can't leave with a stolen vehicle. I am at the "car park" but the doors are closed and I cannot find any "lever" to open them.

How do I need to proceed? Thanks for your replies!

[Oldih]

I believe you need to move a soldier nearby the doors and use the "Use" key to open them. (default is U)

[ghacker]

I looked for the key on every dead body there is and I can't find it.   

[Jason]

Sometimes when bodies are on top of each other you can accidentally check the same body twice. The key has to be there somewhere!

[Supersnake]

The key is not on a dead body, return to the rooms and look again.
It was so obviously placed you will wonder how you overlooked it  .

However, the room it was in may possibly have been destroyed during the explosion.
If that is the case you will have to replay the mission, which fortunately was not a difficult one.