Plane crashed during RTL

My plane made death roll when it is returning in RTL mode.
Is there anyone have a look for reason please?
FC speedybee f405 V3 Emax ES09MD servos and 4S Li-ion battery.

Generally I’d say the plane is flying very well until the end.

The “death roll” was the result of a stall, from high bank angle and low forward airspeed. But the real issue was how did it get there. Until about 40 seconds before the crash the pitch and roll were acting as required. Then for some reason the actual roll starts to deviate from the desired roll. This suggests to me some kind of mechanical issue such as servo/servo wire or linkage failure.

Thank you. When i took parts of plane from crash site there wasnt any servo wire or push rod problem but at home wing servos were smelling very bad. If one of them burned in the air that is possible.

Yes it is possible but should only burn a servo if it was jammed or hunting and pulling lots or current for extended time. Even cheap servos seem to work ok when treated right, what supply voltage did you have on them. Id say you could kill them quick at 7.2v on a standard servo

That’s not a good sign. Even if it does “work” when you test it on the bench I wouldn’t trust it.

Yes I tested with servo tester and 1 of wing servo is not working. Inside everything melted.

No i have matek servo pdb and supply servo voltage is 5v.

Well if it ever worked properly during initial testing it was connected correctly and if it was powered by 5v and not jammed then it just sounds like a faulty servo?

yes it looks like a faulty servo or something happened to servo in the air. Because it worked very well till that moment.