Hard shutoff is Power + Volume down + Home for 8-10 seconds.
After that quickly hold Power + Volume Up + Home and release power button when you see the Samsung logo but keep holding the rest. It should boot into recovery mode shortly after 15 seconds.
You can try doing a wipe data / factory reset if you absolutely have no user data you want to keep on the phone but it most likely won't fix the stuck at boot issue.
You will most likely need to reflash the Samsung Firmware on the phone using ODIN with downloaded firmware from Sammobile or Updato or use the software called Samsung Smart Switch with emergency firmware recovery option selected.
More info here:
https://www.kingoapp.com/root-tutorials/how-to-flash-samsung-stock-rom-via-odin.htm