I can't swim to save my life but I don't mind getting out of my depth.

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I untie knots like alexander,

I get my way with a quick back-hander,

My PC security is an unused plug,

Why fight my battles when I've hired a thug,

They say I swordfight just like Indi,

I call this bolt cuter 'The Master Key',

I keep my best cards behind my back,

And my favourite trick is a brute force hack.

What am I?

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Oh! And here's a stumper that's got me stuck:

If stack exchange goes down, how on earth do they fix it?!