So if the problem happened instantly at 0210, .
THE problem? Clearly ACARS is saying something is happening at 0210.
Yep, THE problem. Yes, we know that something started to happen around 0210 that looks a lot like pitot icing, but might be something else. But many have asked why pitot icing caused a problem here and it didn't for many other planes.
So I presume that the reports starting at 0210 are indications of Bad Things, but that they are not THE problem, since they don't seem to be sufficient
by themselves. I presume THE problem (disorientation, food poisioning, both pilots asleep, pick a reason, whatever) occurred subsequently to the first 0210 report, but maybe before the last 0214 report. This is of course pure supposition - but at this point supposition is all that we have informaiton for.
the plane has to turn around in zero distance and cover 30 miles backward. Since it isn't likely it turned around in zero distance and it isn't likely the problem happened exactly at 02:10, the plane probably covered closer to 100+miles horizontally from failure to impact.
Keep in mind
1)that would be re-entering that cell(indications that particular one reached FL500) they just passed thru (when viewed from above) to go toward the south.
Yes it would. You will note I did not say they voluntarily turned around. I said "X marks the spot" was a spot on their track before the 0210 position. They got there somehow.
2)as they couldn't reach 100 miles in 4 minutes, how would you then explain the termination of messages at 02:14?
Explain? I don't, insufficient data. I can guess lots of things. Maybe they lost electrical. Maybe they crashed at 0214. Maybe something else happened. Keep in mind we don't know where they were at 0214. If the flat spin scenario will get you 'straight down' to the ground in 4 minutes starting at 0210, maybe some other spin will get you 30 miles south of 'straight down'.
While I try to figure out how to do that why don't you work on a solution for landing with mostly a vertical descent onto their belly upon arrival at the backtracked debris zone.
I already did that several posts back. Stall it in nose high at about a 45 degree glideslope. The acceleration vector will be about normal to the "down" direction in the cabin, and the tail hitting first will rip off the VS in the manner the BEA wants it to go.