Apple Watch died after charging.

Hi

Try force restarting your watch: press and hold both the side button and Digital Crown for around 10 seconds, until you see the logo.

If that does not help, next try charging your watch again for around 2.5 hours, making sure that you follow the charging instructions here:

Check your battery and charge your Apple Watch - Apple Support

After that time, if it has not already restarted automatically, remove it from the charger and:

- Try restarting it (by pressing and holding the side button until you see the Apple logo).

- If necessary, next try force restarting it again.

More information:

If your Apple Watch doesn't respond or won't turn on - Apple Support