My Apple Watch started a update and has paused and will not continue

FWIW, a lot of people have problems updating a series 3 watch due to insufficient memory.

To Free-Up Storage

For songs, see:

Remove music from Apple Watch - Apple Support

and for pictures, see the "Limit photo storage on Apple Watch section in:

Choose a photo album and manage storage on Apple Watch - Apple Support

To delete apps on your watch, see:

Delete apps from your Apple Watch - Apple Support

Also, try unpairing and pairing your watch again and restoring from the backup just created in the unpairing process. This deletes all temp and corrupted files and re-indexes the file system. This should result in no loss of data and in some cases can free a lot of storage.

Unpair and erase your Apple Watch - Apple Support

Set up your Apple Watch - Apple Support

Also see:

If you don’t have enough space to update your Apple Watch - Apple Support

Another option (maybe even better, if possible) is to take to make an appointment at the Genius Bar in an Apple Store near you and let them update it.

Genius Bar Reservation and Apple Support Options - Apple