Issues Booting Up
If your MacBook fails to start up correctly, then it is probably best to boot it up in Safe Mode. The operating system will boot up with the least required software and run diagnostic checks to resolve issues which may be contributing to the failure.
To enter safe mode, simply turn on your MacBook and hold down the shift key. You can release the shift key once the apple logo has appeared and disappeared on the screen.
Spinning Beach Ball
The spinning beach ball is Apple’s way of signifying a delay in processing, which could be a result of apps running in the background, or a lack of available memory resources. One idea is to free up some memory on your mac, by doing a clean-up of any large files, or programs which you no longer use.
You can also open up the Activity Monitor window to get a real-time view of the CPU and memory that each app is using.