50 min layover Amsterdam (UK->AMS)

Hello!

Yes I have already booked this flight. No, I cannot cancel it.

Various sources say this is doable but a lot of them are Schengen to Schengen, or other countries such as the USA. Has anyone from the UK done this? My next flight after Schiphol will be to Berlin. How fast will I have to skedaddle? I'm only bringing a backpack, so luggage isn't a worry. I've booked the furthest up seat that I can.

If I miss it, how are the trains? I'm perfectly happy to sit on a 5+ hour train if I can't catch another flight down.