I have a 1100 mah 4 cell reciever pack in my airtronics system. The thing worked pefectly until lately.
I picked up an accucycle plus a couple weeks ago and after playing with it a bit and doing the discharge thing and all I went flying one day. About 30 seconds into the flight I lost all control.
We checked voltage and got a 3.6 volt reading.
OK OK I figured I did the accucycle wrong and didn't get a proper charge.
I went back to the wall charger until I got the accucycle figured out. I fixed the plane and charged the battery and flew 4 nice flights without a hitch.
Couple days later I charged the battery again with the wall charger. Took the plane out and about 30 seconds into the flight I lost all control again. Checked the battery and got a reading of about 3.5 to 4 volts again.

MY CONCLUSION.
I have an intermittant short in one cell.

Do you agree?

That's probably a good diagnosis, but do the rest of your testing on the ground.