I downloaded kodi on my FireStick but it won't install it, how can i fix it

Hello! It is a good question, and I think that Kodi for FireStick is a great choice, you will not regret it. I recommend that you have a look at the tutorial from https://www.firestickhow.com/kodi-firestick.html where you will be able to find some awesome instructions on how to install Kodi on your FireStick. I am sure that you will be able to easily do it with its help and use Kodi very soon

Firestick allows installation of Kodi and you can easily setup kodi on Android devices which also includes firestick How to Install Kodi on Fire TV Firestick Easy Guide

Once that is done, feel free to setup 101 Best Kodi Krypton Addons for March 2018 Working List which will let you stream movies, tv shows, sports, cartoons and a lot more of stuff.

You should first clear out the existing edition of kodi off the firestick. Once that is done then proceed to Kodi.tv and re-install it again. From that point you need to install a new kodi build. To do this, check the link below. Theres guides to help you through the process and even a few youtube tutorials as well.
Best Kodi Build List for 2018 Must Read Before Installing BestBox

Why would you buy kodi installed FireStick when you can do it yourself in a few minutes? I mean, OK, you don't have any problem to spend some additional money in buying Kodi preinstalled Fire Stick but what if you get problems later? It is always better to know how to install Kodi on Firestick as it will help you in future too. How to Install Kodi on FireStick

You can reinstall kodi on firestick with a lot of methods but one of them is given as follow
Similar to other methods, this method too requires you to enable installation from "Unknown sources." Once you do it, follow these steps.
Before these steps
STEP 1: Search FireDL on your Fire Stick.
STEP 2: Install FireDL and Open it.
STEP 3: Type 600003 at the top blank space.
STEP 4: The above code will automatically convert to the Kodi APK URL and download will start without any further actions from your side.

You can then install some great addons and builds to further enhance your experience.
19 Best Kodi Builds To Experience The Colors Of Kodi

Here's how you Fix Kodi Not Working: Fire Stick Kodi Not Working Fix FireStick Fire TV Now KFire TV and here's how to install XMovies8: https://kodifiretvstick.com/xmovies8/

Follow the link please for instructions. https://seo-michael.co.uk/tutorial-how-to-install-kodi-on-a-firestick

Try this link to download: kodi apk Download Android APK GAMES APPS for Kindle Fire
This link for step by step how to install guide: Step by Step How To Install Any KODI Add on or Repository

Hope they help, Merry Christmas!!!