it could be the battery or the connections or the crystal.
I lost a model like that, but when I got all the piece back to the
work bench, everything was working fine, until I wiggled the battery's wires.
The battery's wire inside the heatshrink wrap got damage from a previouse crash.

I lost another model after I transfered the RX to it. Moslty likely a crack crystal.
Everything tested out good on the ground, but after I got in the air, no single.

of course most of the guy said ...pilot error.lol...I'm not that slow.
maybe they're right, since the pilot and the builder is the same person
It's nice to have a fleet, thou