Based on the information provided, it seems that your ASUS X407M laptop is not working properly after upgrading the RAM to 8GB. The LED indicators are lighting up but there is no display, and the fan is not spinning.
Here are a few things you can try to troubleshoot the issue:
1. Check if the RAM is properly installed - Make sure the RAM is properly seated in the slot and locked in place. Also, check if you have installed the correct type of RAM that is compatible with your laptop.
2. Reset the BIOS - Sometimes, the BIOS settings can cause issues with the RAM upgrade. Try resetting the BIOS to its default settings by removing the CMOS battery from the motherboard.
3. Check the display connection - Make sure the display cable is properly connected to the motherboard and the display panel.
4. Remove the battery and power source - Remove the battery and power source from the laptop, then hold down the power button for 30 seconds. Reinsert the battery and power source, and then try turning on the laptop.
5. Test the original RAM - If possible, try testing the original RAM that came with the laptop to see if it works. This will help you determine if the issue is with the RAM or with the laptop.
If none of these solutions work, it is possible that there may be an issue with the motherboard or other internal components. In this case, it may be best to seek professional help from a computer repair technician.
