I just had my alternator rebuilt to try and rectify an intermittent problem where the car would die exactly as you described. All 3 times it did it the dash lit up like a Christmas tree and the car completely died within 20 seconds. In each case the battery was completely dead but after charging it the car would run perfectly fine for months with no indication of a problem and no error codes.

When I took the alternator in it was working but the ceramic insulation on 3 of the diodes were cracked so I just went the full rebuild for $275.