Hello, Welcome to the Community. We understand how frustrating it is when the phone will not update and crashes. Troubleshooting steps available for this occurrence includes the following:
Wiping your cache partition
1. Turn off the device.
2. Press and hold the Volume Up key, then press and hold the Side key.
3. When the green Android logo displays, release all keys ('Installing system update' will show for about 30 - 60 seconds before showing the Android system recovery menu options).
4. Press the Volume down key several times to highlight wipe cache partition.
5. Press Side key to select.
6. Press the Volume down key to highlight yes, them and press the Side key to select.
7. When the wipe cache partition is complete, Reboot system now is highlighted.
8. Press the Side key to restart the device.
If these didn't work try updating your phone with your computer using Smart Switch
Start with download Smart Switch for your computer by going to this link - https://www.samsung.com/us/support/owners/app/smart-switch
Install the Smart Switch on your computer. Once done restart your pc to make sure that files needed are installed correctly. Then connect your phone using the cable that came with your phone to your computer.
Then an option "Update" should appear and that should update your phone if not then you must set up an appointment to have your phone get software re-flash by going to this link to look for available service center near your https://www.samsung.com/us/support/service/locations/
If these steps do not help, you will need to follow up with your service provider.