i click on my vm to start but it says " (vm name) failed to start" heres the troubleshooting log output - Pastebin.com
This solution worked for me Cannot run Gnome Boxes - #4 by puneetse, simply do sudo usermod -a -G kvm $USER.
did it and rebooted.didnt work
Did you install the flatpak or the bundle?
I installed Boxes a few months ago, but I remember I had issues with the bundle first and then with the flatpak. I think, what I ended up doing was: install bundle, remove bundle, install flatpak, remove flatpak, install bundle, and it worked 
I never looked at what was the reason that it worked the second time I installed the bundle.
Anyway, it may worth a try if you are out of options. Also, it could be your virtual machine configuration and not related to the installation of Boxes.