Finally, I have successfully flashed the N9 and tried to do a basic set up, but everything is going wrong

1) Not able to enable developer mode, it gives "Installation packages are missing". Any alternate way to enable dev mode ?
2) openrepos website is not opening in N9 default browser.

With out file manager I'm unable to install any deb files. Any help will be very useful to bring back the N9 in 2022.