Hi Tether10 & welcome to the forum,
Sorry to hear that you are having these issues. The NDX internals are quite different to the NDS, so I wouldn’t think it would be the same problem.
Have you tried fitting new batteries in the remote (just to rule that out)?
Could you try a factory reset please?
Press & hold front panel OK button & navigate to Factory Settings, then navigate to Reset All Settings.
This will set the unit to the default IR code, which should match the remote in Aux, i & disp mode.
If you wish to provide me with an RMA number, I can check to see if anything was done to your unit that may have influenced your i-radio problem, such as a new streaming card being fitted.
Regards
Neil.