Hello, it would be good to know if the Laptop has valid its guarantee and on the other hand if it receives battery charge, without making some measurements it's difficult to give an accurate diagnosis; it's possible that it's an element of the board (circuit) it's necessary to measure the voltage and other components to determine if there is a problem with the voltage delivered by the charger.
We can perform a battery reset to check and have an idea.
Your D620 probably has the Nvidia Graphics (Video) card that was a manufacturing defect well documented all over the internet. I have reflowed the video card on quite a few of these laptops.
Below are some excerpts from the user manual.
Solid green power light and no beep code and no video during POST
The monitor or the graphics card may be faulty or incorrectly installed.
Check the diagnostic lights to see if the specific problem is identified. See "Video and Monitor Problems."
Open the Calculator program on the laptop (in Windows or Linux).
Click on the start menu.
If your operating system doesn't support searching from the start menu then look in the application listing for Calculator..
Check all sides of the laptop for a switch to turn on the wireless, if not you look at the keyboard make sure there is not a key that has the wireless on it . If you see the wireless on the key you must hold FN key and wireless key to activate. If the problem is not wireless, and it is just networking. Go in the control panel under network and sharing, open that and look for change advanced sharing settings (usually on the right side upper corner) open that and make sure turn on network discovery is on turn on all items ..
No. Factory reset wipes all settings and will require you to enter them again to get connected. You're better off using the help function in the Network Wizard to troubleshoot the problem step by step. If it's a windows machine it might be able to repair itself through this process.
if it is the password that pops in blue as soon as u start up mate the best bet buy the cd from ebay i have one but i found it easier going to the computer shop cause they have the hardware to do that plus if u google it pay a company who remove bios passwords you WILL HAVE TO REGISTER WITH them but make up something cause they ONLY do it for commercially goodluck if you dont get anywhere tell me and i,ll help you ok.