Overheating is very common with the Inspiron 9300 if you leave it on for long periods of time, but that does not necessarily mean anything is wrong with your laptop. Your laptop can overheat after using it for just 10 minutes. It can also overheat from watching videos, playing games, or streaming/downloading online content. To reduce this overheating, use the laptop in an air conditioned room and on a stable flat surface like a desk, instead of a cloth or fabric surface like a blanket or pillow. This placement allows for better airflow. If your laptop is getting too hot and shutting down due to overheating, then I would definitely try cleaning the vents with some compressed air to get rid of any dirt buildup. You may need to clean the vents regularly. If cleaning does not help, then you may have an out of date BIOS. To update your BIOS, type in your Service Tag on the Dell Driver & Downloads website to download and install the proper drivers for your computer. Please refer to the troubleshooting page for...
Try typing into a different program to check if the keys are not working. If keys still don’t work, turn off the laptop, remove the battery and unplug it, press and hold the start button for 60 seconds, then place the battery back in and turn the laptop on. If this does not work, keyboard is broken and must be replace.
Start with boot key combo Command-Option-P-R https://support.apple.com/en-us/HT201255 Then boot from OS X install disk. Run disk utility disk first aid. If it shuts down while in the middle of this it may be a thermal issue. Is the fan clean? How much room is left on the hard drive? Replace hard drive? Are you installing the RAM symmetrically? Maintaining parity? If there are four slots of RAM, then install on 1 and 3. Equal amounts in both slots. There will probably be a very little 1 next to the first slot on the logic board. Reseat all cables connecting your hard drives. Make sure no dust has accumulated on the internal components. Blow off with compressed air if dusty.
Make some space on your boot drive by deleting some files on your boot drive. If you have made some space on your boot drive and it still won't boot, it is possible that you over wrote your master boot record (MBR). If this is the case you should be able to restore without formatting your entire disk. Keep in mind you can install large applications on your 750Gb disk and they should run just fine. Also, you can change where FC caches. Switch this to your extra disk as well.