ACARS
Both the windows messages are not about the windows being open. The code WHC stands for Window Heat Computer, and this has to do with de-icing.
As for a emergency decent, this is procedure for either cabin depressurization, or fire/smoke on board.
A quick 90 degree turn? Either to get out of the flight lane (not sure if this is company procedure), or just airman-ship to keep positive G while pitching the nose down for rapid decent.
Why no communication? Either the pilots were too busy, or simply the radios were not operating anymore. Did they change xponder code to 7700?