Perhaps I should not have said anything?
Went flying with my AcroMaster - AR6200 Spektrum rx. Drove home to solder a connector to a new Hacker/Flightpower 3s2500 pack, charged the battery and went back to the flying field. Left the model in the car for the whole time. Outside temperature approx. 22°C, but full sun. Back at the flying field, the AR6200 would not link to the tx - went straight into Smart Failsafe. That has never happened before. Back at home I re-checked and everything was working fine. I am puzzled.
Jürgen