Guide to Enable Developer Options on Amazon FireStick
Here's how you can make the Developer Options reappear:
STEP 1: Go to the FireStick Settings.
STEP 2: Select My Fire TV.
STEP 3: If you cannot see Developer Options on the screen, click on About.
STEP 4: Click on Fire TV Stick quickly 7 times.
STEP 5: A notification at the bottom will appear, saying "No need, you are already a developer." This means you have enabled Developer Options.
STEP 6: Press the back button once or navigate back to Settings > My Fire TV, and you will now see Developer Options.
Now that you have successfully enabled Developer Options, you can go back to the Installation Guide for Amazon Firesticks and follow the rest of the steps.