MacBook app that won't quit, is still running, but at the same time won't open

Right-click or control-click the app's icon in the Dock and make sure Options > Open at login is NOT selected.

Then press and hold the power button - up to 10 ten seconds or so - until the computer turns off.

Then restart the Mac again and check the result.

kajaen wrote:

I have a macbook pro (M1, macOS sequoia15.6.1) with an app (Interactive brokers desktop app if it matters) that won't open. However, I'm not able to quit it either. There's a black dot under the app in the dock, and when I try to force quit it, nothing happens. I'm not able to restart my mac or uninstall the app or move it to the bin because "IBKR (the app) is running". I have shut off my mac using the power button on the keyboard, but that doesn't do anything either. When I turn it on again the app still has a dot under it, but won't open.

What can I do??

Pleas and thanks!

After your Force Shutdown out-lined by D.I. Johnson above...

if no progress try a SafeBoot Start up your Mac in safe mode - Apple Support

Login and try making changes to that problem app or delete it, what ever the goal.

Reboot as normal and test.