I recently got a 10th generation Kindle and was excited to set it up. But boy, was I in for a surprise!
The instructions I found mostly talked about setting up the Kindle part, but completely missed the actual tablet registration process. My new Kindle kept displaying a 6-digit code with no clear instructions on what to do with it.
After hours of frustration, I finally discovered the solution wasn't in any manual. You have to go to Prime Video > My Stuff > click the settings gear > select 'Register' and THEN enter that 6-digit code. Who would've thought?
This experience taught me that sometimes the official guides aren't the most helpful. If you're stuck with the same issue, try my method - it saved me from returning what could have been a perfectly good device!