Forgot something important to fireworks - if you have a Nikon DSLR you need to be in 'Bulb' mode for fireworks. For a Nikon D7500, set the camera on Manual mode and use the main command dial to select the shutter speed immediately after 30 minute exposure - Bulb. You then press the shutter button to start the exposure and press it again to stop the exposure. I used a remote to control the shutter as I didn't want to shake camera or tripod and introduce camera blur into the picture.
I remember now that in class there was a big video screen and the teacher showed a film of fireworks going off and we took pictures of them. They came out like they should. I had never heard of bulb mode until that day. I sure as hell didn't know how to find it! Canon also has a 'bulb' mode for long exposure. Not sure how to get to it. Most likely pretty similar.
Longball