I spent the last two years ghost-writing when I should have been flying. My 350 QX and its predecessor, the 200 QX now fail to initialize. The 350 QX repeatedly emits 3 descending tones and its display flashes red. The 200 QX constantly beeps and appears to be in Agility mode, but does not respond to inputs. It is likely that the 350 QX onboard battery that maintains the GPS data has died, but the 200 QX does not use GPS, so I did not think it had any onboard battery. I flew both like antique cars - well kept and only flown for fun. Is it possible to replace the 350 QX onboard battery and not lose all programming?