Iphone 11 restarting to apple logo

Iphone 11, which hasn't been backed up for a while, switched to apple logo, then tries to restart every minute or two but never gets past that logo. I have been successful in recognizing it with Itunes after physically connecting it then doing the volume up-volume down-power button sequence. It then gives me the option to 'update' or 'restore'. This is a client's device and I'd like to update it, but there are a lot of photos and data present which I'd like to be able to recover. Any info would be greatly appreciated.