I really need to know if it is wrong for a born-again christian to work in a company that produces alcoholic beer for example guiness.

It is not wrong ! !
Forget about all those who will tell you it is wrong cos they clearly do not know what they're talking about.

To answer ur question easily, you first need to know if consumption of alcohol is wrong.
Answer to that is : no, consumption of alcohol is not wrong; over indulgence in it(which could lead to drunkeness) is what is wrong.
Breweries produce alcoholic drinks for responsible consumption by their consumers.
It is the responsibility of the consumers to be responsible in their drinking.

So, in conclusion, to work in a brewery as a Christian is definitely fine!

Take a look at this:

Automobile companies produce cars. Cars are good for moving one from one point to the other(transportation).
But, overspeeding with cars is wreckless and can lead to accidents which could claim lives.
Do we now say driving of cars is a sin?
Do we now say that working in an automobile company is a sin?


That is exactly the same scenario with brewries.

And besides, there is no where in the bible that consumption of alcohol is regarded as sinful; rather, the overindulgence is what is regarded as sinful.

Please read through.

https://www.nairaland.com/nigeria/topic-161381.0.html