I was in the middle of a project, slicing, etc, then went to print, I get a message about ‘please update firmware’ and now when I click anything in the Bambu Studio it just does the Windows error DING! and nothing.
It seems I’ll have to force close the application and lose all my work. 
*edit
If I hover over the red X of Bambu Studio, in the taskbar, like I’m going to close it, I see the printing prompt is still open in the application, but I can’t actually get to it. It’s not a separate window so alt+tab does no good
How many monitors are you using? it might be open on a different screen ? happened to me once when I undocked my laptop from another screen. Right-click the program on the taskbar, and then click Move . Move the mouse pointer to the middle of the screen. Use the ARROW keys on the keyboard to move the program window to a viewable area on the screen.
Invoke Task Manager and kill the process for Studio from there. It won’t care if there’s a dialog box open.
I’ve seen something similar to what you describe. I think it’s a Windows bug that’s hard to hit. But when you do something that opens a modal dialog (meaning the app is frozen until the dialog box is dismissed), if you get an extra click in there before the dialog appears but after clicking the button that opens the dialog, the dialog opens behind the app’s main window and you cannot see it or bring it to the foreground to close it, or to be able to exit the app.
You can try alt-tab to see if the alert for the update got buried under the main window. If it’s still open, it won’t let you do anything in the slicer, including close it.
RocketSled is correct. The ‘send to printer’ dialog where you checkbox calibration, ams enabled, filament location, is indeed modal.
I was able to hover over the red X in taskbar and it pops up. Just no way to click it since it’s behind Bambu Studio.
Had to force closed, luckily the previous project was restored.