Support requiring serial# before helping me, but my phone is stuck on logo and does NOT have printed serial

6/3/19 Tried to download latest update when error occurred. Now phone is stuck on the logo screen and I can't restart by holding the down volume and side buttons. Tried to start a chart and tried to call support but my serial number is required first.

I have no way to view this information since my phone is stuck and does not have the serial printed anywhere on the device.

My only option is let battery die or take off from work and drive 20 miles to Apple store. :(

Any advice?