I have decided that I don't want to return my HDVR3500. I thought I was getting a quad-core with plenty of RAM so I could use it for both FTA and IPTV. But I didn't expect it to receive ACM when I first tried it -- a very pleasant surprise! I also like the fast blind scan. Since I do a lot of KU feed hunting with my BirdView, the blind scan speed really helps. In addition, the fast forward and rewind functions are the best that I have seen in any FTA receiver.
From the CPU usage tests reported previously here, it doesn't seem like the CPU-intensive portions of the firmware are optimized for multiple cores. Portions of the code where it spends most of its time need to be rewritten to be multi-threaded. This receiver would really benefit from that.
I just tried the UP and DOWN arrows here and it started playing the previous or next recording in my list. Maybe there is a corrupt recording left over from when you had the newest build?
I deleted all of the recordings that were stored by the DVR in case one of them was corrupt and I created 3 new recordings. After making the new recordings I pushed the up and down buttons and the change from one recording to the next DID work as N6BY described. BUT... when I reached the last recording in the list of recordings and when I pushed the down button again, instead of looping back up to the top of the list of recordings the remote control was dead and any inputs that I made would not work. It seems that if you are watching the last recording in the list and if you push the down button again that the unit should loop back up to the first recording in the list and to not lock up the remote control ability requiring a hard reset. The only way to activate any inputs was to reset and reboot the unit using the master off switch on the rear of the unit.