Power problem confused

Hi guys I've recently had a problem with my r50 it start as soon as the U.K got cold, I was parking up and suddenly the dash went crazy and power steering hardened up, I had a thought that the pump was about to fail, but when I went to the car today I unlock it and went to start it but it was completely dead, the battery still had 12v charge, and when I checked the alternator the other day it was charging at 14.4v , so there is nothing wrong there, but anyway as soon as I got back into the car I pressed the unlock button on the key fob and put my key in and everything came up as normal. Can the forum shed some light on my situation. Here's my video link for the steering problem.

youtube.com/watch?v=_VIkUe2AI5M&feature=plcp