I Have A Compaq Evo N600c Laptop No Power Help!!!

I’m happy to help further over the phone at https://www.6ya.com/expert/james_d4449ffdf318a2c3

Entering and Exiting the BIOS Power on the system. Press F10 when the blinking cursor appears in the upper-right portion of the screen. Select a task from the following menus: File, Security, or Advanced.
To exit the Bios, select the File menu. Choose either Ignore changes and exit or Save changes and exit, and then press Enter. When you are prompted to confirm your choice, press F10

Do you see any lights on the laptop that are on? If you see any lights and only a black screen, then more than likely your video chip on the motherboard has gone out. Some local shops might be able to replace the motherboard it might be cheaper than buying a new laptop. Good luck

don't waste money on buying second or used.
buy original from near HP store or order online. check HP center near

Go on this site and download it...

http://pdftown.com/Compaq-Evo-n600c-Service-Manual.html

wrong battery for it or connectoers on battery dirty could be the charger for the battery is bad and shorted battery out

When you hooked up external monitor, did you switch to it via "Fn" keys?
If it did not help, then it's GPU ot North Bridge on the board that needs service.

Clean heatsink and fan.

Wouldnt fancy taking one apart myself, replacement ones are not very expensive, look here on battery trader , Compaq Evo N600c laptop battery

You can insert the OS installation CD and hit F11 or F12 to get to the boot menu. The you can wipe out your hard drive and put a fresh copy of windows on it.