It's good to hear that you were able to resolve the issue and get your system working again. The steps you took, such as disconnecting external drives, power cycling, and waiting before restarting, seem to have helped in this case.
Sometimes, unexpected behavior during the boot process or at the login screen can be caused by a variety of factors, including temporary glitches, conflicts with external hardware, or issues with system processes. Your troubleshooting steps effectively addressed these possibilities.
If the issue does not recur, it may have been a transient problem. However, if you encounter similar problems in the future, it could be worthwhile to monitor your system for any patterns or possible triggers. Additionally, keeping your operating system and drivers up to date, as well as maintaining backups of important data, is always a good practice to prevent or mitigate potential issues.
If you experience the same problem again or encounter new issues, you might want to consider further diagnostics, checking event logs, or seeking assistance from technical support if needed. Remember that intermittent issues can sometimes be challenging to pinpoint, and their resolution may depend on specific circumstances and system configurations.