Just came back from almost two weeks of vacation and used my new D3500 quite a bit. Got some decent pictures, but ran into problems several times. We were away from Internet a lot and I did not have the manual, so that confounded my issue, which was . . .
Several times I was in the middle of taking multiple pictures and it would stop allowing me to take any more. Looking back, the issue MAY have repeated when using 'Live View' to take a picture, as I remember seeing the green 'focus box' turning red (don't get that in the viewfinder), and it not shooting. I could not remember at the time how to tell how many pictures were left on the card (have since figured that out, duh!). I immediately assumed the card was full, shut the camera down and dropped in a new card. It was NOT full. One time I changed both the card and the battery as the last battery symbol was flashing.
In retrospect, the cards had plenty of room left on them and I think shutting the camera off and turning it back on solved the issue. Question is, what IS the issue? I've googled this for the D3500 and not found anything yet. There is no firmware update. It's very inconvenient.
Thanks for help or suggestions for this new DSLR photographer.
John
P.S. Just found this about 'DBS' (Dead Battery Syndrome) . . . did have 'Low' battery one time, the others, changed the card.