Identifying and resolving an unknown item on the screen
What is it on the screen and how can I fix it?
Apple Watch SE, watchOS 10
Question marked as
That symbol is made to resemble the charger-puck and indicates that the watch needs further charging to power on. Apple's own Support Article mentions the following:
If your screen stays blank even when you press the side button, or if the charging cable icon appears, you may need to charge your watch for up to 30 minutes before it will turn on.
If your Apple Watch won’t turn on or won’t charge – Apple Support (UK)
If the watch stays in this state, and doesn't react to pressing/holding the side button, make sure that you followed the instructions in the above mentioned help article, section "If your Apple Watch won’t charge", closely.
Should you still experience charging-issues, contact Apple Support for further instructions.
Hope I could be of help!