MH370 did not break up or crash at the point where the Flightradar24 feed ends.
Otherwise something would have been found by now.
So it kept flying with the transponder off.
But why no mobile phone contact?
1) Too far from any cells.
2) Passengers incapacitated by depressurisation.
The latter theory would fit in with the garbled radio transmission.
It would be interesting to know the cause of such a decompression event.
Bungled Hijack attempt? This might also explain the transponder stopping transmission.
Structural failure from the wing repair?
Small explosion?
So where is the 777 now?
If it had crashed over land the ELT would have activated and been seen by satellites. This is why they are not searching the landmasses.
So it is at the bottom of the sea, where the ELT transmissions can't be seen.
But the reality is that it could be anywhere in a radius of well over 1,000 miles.