Unable to shift into fwd or Reverse-2015SV

I got the "T/M system malfunction" warning this morning, with the battery symbol lit up. It was 7degrees out and I had just removed the trickle charge cable with 100% capacity showing. The shift lever would not engage either forward or reverse but would only go into neutral. Called the Nissan service and they had no suggestions except to have it towed into them. Tried in vain for about 15 minutes, and walked away-returned for another try 15 minutes later and everything was normal. What happened?

If you can't get it into READY mode (green car w/arrows), it's probably a low 12 volt battery, that can be remedied by jump starting. If it continues, esp. after you charge the 12 volt w/a real 12 volt charger, the 12 volt battery might be bad.

Measure the 12 volt voltage with a multi-meter/volt meter after the car has sat for many hours (before turning on the car). I suspect it's low.

Definitely sounds like a 12V battery issue. If you have Leaf Spy, it will tell you what the voltage level is on the 12V battery. In my experience, anything below approx 12.8V can cause the "T/M system malfunction" warning to appear.