Yes, I had a similar problem with my 3500SD. Remote would function perfectly sometimes, and then other times, like it wasn't there as far as the receiver was concerned, but button flashed like it was sending. The a few weeks ago, the unit was working, but the display gave strange characters. I turned it off, and then it wouldn't come back on. I took it apart and checked the power supply. All seemed normal, except the 3.3 volt DC line had only 2.5 volt DC and showed some AC signal, as measure on my Fluke. I replaced both of the 100 mfd, 10 VDC capacitors on the 3.3 volt supply and now it is running fine. The capacitors measured 3 mfd on the meter, not 100 mfd. Usually these capacitors last several years, my receiver is about 2 years old, so this is what I would consider a premature failure. Good Luck, I hope this helps.
Migold