Re: Why won't my fan turn off on my Macbook?
It sound more like some heavy process are ongoing in the background which causing the fun to run non stop, specially if the process end up in a boot looping.
While the computer is on and the fun turning, open up your activity monitor app, and spot out which of the process is using high amount of CPU. Highlight that process and kill it by clicking on the x button at the top left of the activity monitor window.
If it's a software that you install causing it, you can uninstall that software and reinstall it, if it's a system process important for the OS to run, then you will need to reinstall your OS. Note that reinstalling your OS won't erase your files and apps, also you can google about how to reinstall your OSX while keeping your files steps by steps instruction.
Should the fun keep on running full speed after all these, take it to an Apple Store for service if possible.