[Grammar] before + present perfect

[Iryn_]

Hello, dear forum users!

1) He worked as a shop assistant before he became a manager.
2) He worked as a shop assistant before he has become a manager.

Be so kind to say whether both of these sentences are correct, and if yes, how's the meaning different.

 

[Tdol]

The first is fine. The second doesn't work for me.

 

[Iryn_]

Could you explain why?
for example, if he's still a manager, there's connection to now, can't we use present perfect?