I followed the instructions I found on this site but didn’t get very far. Clearing the Apps Cache worked fine but when I tried to clear the System Cache, I couldn’t get past the beginning. The instructions say to hold the power and volume-down buttons down for 2-3 seconds. That didn’t do anything but turn the phone back on and turn the volume down.
With phone powered off, press and hold Volume Down, then press and hold Power
the phone needs to be fully powered down (from what your description you just turn the screen off)
to power down press and hold the power button until the power off pop up appears on the screen then tap that on screen popup
Right. The instructions just said “phone off”. I didn’t realize it meant powered down. I should have. Thanks for making that clear. All is fixed.