I have run across an issue where Software Manager hangs at the spash screen after asking for a password. This seems to only happen if it had been previously closed abnormally. The fix that seems to work for me was:

Open a terminal and run:

ps -A

There should be a line that lists “splash.py” like below:

3323 ? 00:00:10 splash.py

The first number is the process ID (PID). Use the “kill” command to end it:

sudo kill 3323

This should close the spash screen. Now we will need to clean up the program a little bit. Run the following commands:

sudo rm -vf /var/lib/apt/lists/*
sudo apt-get update
sudo apt-get clean

I ran the clean option just as an opportunity to clean up the cache while I was at it, it is purely optional. Now, re-run it as you normally would through the menu and it should start up. There still will be a little bit of a pause at the splash screen.