Hi The Bee,
I am glad to know the issue has been fixed. Surely I will try to help you with the overheating problem as well. You can follow the below mentioned steps to keep your laptop cool:
1. It is recommended to use the Laptop in a Room temperature of 0°C to 35°C (32°F to 95°F) with a Humidity level no greater than 90%.
2. Use compressed air to clean the vents on a regular basis. You don't need to open the chassis to clean the vents. Sometimes the accumulated dust is not visible by simply looking at the vents. To properly clean the vents:
a. Power off the System
b. Unplug the AC Adapter
c. Remove the Battery
d. Use `Compressed Air Can' to blow the dust out of the vents. Do not use your mouth to blow the dust out of a Laptop. Use the `can' according to the directions on the side of the `can' as you can cause damage to the computer if used incorrectly.
3. Outdated BIOS can cause heat issues by having an outdated temperature table for the system. Click here
to download the most updated BIOS for your Dell Inspiron 3520 System.
Note: Plug your computer to a good, working UPS before you update the BIOS. If you experience a loss of AC power or a significant voltage sag/spike during the BIOS flash, you will either have to buy a new BIOS chip or buy a new motherboard.
Do reply with results.
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Thanks & Regards