Hi Irie1221!
Sorry to hear that s7 is acting up! While this might not work while in a boot loop. Have you tried replacing the phone into recovery mode? When you do this, the splash page will show the S/N for the device.
To do so on a Samsung S7 device:
Hold the volume up key, home button, and power button at the same time for a few seconds. If it doesn't go right into the boot loop the information should be visible on the recovery page.