Let's access your QuickBooks Online (QBO) using a private window to rule out any browser-related issue. But before we proceed, what specific error message are you getting.
Here are the keyboard shortcuts:
If it works, clear your browser's cache for the system to start fresh. You'll also want to use a different browser.
For your future reference about QuickBooks, here's a link for more information: Account Management.
Please let me know if you need further help. I'll make sure to help.