According to data from zoom.earth there were actually CBs in the area. The crosshair in the picture below is an aproximate position of the plane when it was at FL100. There is a chance that the plane was hit by lightning which led to autopilot disconnection and also temporary blindess to pilots could have made the airplane uncontrolable.
Originally Posted by
physicus
No significant convective activity visible in the 07:40 UTC high res satellite imagery.
Channel B13 cloud top temperatures (coloured < 41C)
true colour visible image.