Alternate Reality -- Underwater Alien Library

Here we go again.  Weird dream time.

This was an alternate reality, around WWII times.  It was an alternate reality, because in the dream, Germany wasn't the only country with submarines.

This one German captain was testing a "scattershot nuke" torpedo, an innovation he had contrived.  In order to test it, the target was this alien library, submerged under the Atlantic.

The world had known about the library (very high-tech even by WWII standards) for 4,000 years.  It made itself known with periodic broadcasts of some sort, perhaps telepathic.  Anyway, the library had been self-maintaining for a very long time, but it was beginning to break down pretty bad.  Attempts had been made to dock with it and try repairing it (by different countries that had submarines), but every attempt had been met with disaster.  Many a submarine had been torn apart by the currents surrounding the plateau where the library sat.  (But sometimes a submarine could connect and get electrical power from the towers at the library, don't ask me how.)

Now, if you could get into the alien library, what information would you seek?  What technology would you want to bring to the surface?  Would you share it with the rest of the world, or would you try and get rich off of it?