I DON'T KNOW IF WITH 1.12 IT WILL WORK....
That said, you have to put the .bin you want to install into mrpackages folder you should have in your Kindle root directory, and after that, click on the latter button "Install MR Packages".
For info:
https://www.mobileread.com/forums/sho...ht=MRInstaller
The reason it flashed back to your home screen when you tried is that it did not find anything into mrpackages directory