My screen does not turn on - Compaq Presario R3000 Notebook

• Remove all power (adapter power Cord and Battery (for laptops))
• Hold down the ON button for 30secs (dispersing internal voltage)
• Plug the power cord in only (ie leave battery out, for the moment)
• Turn on

Check your power adapter. Plug it in to a known good power receptacle. See if the power adapter has any lights that light up to make sure it is getting power.
Take the battery out of the laptop and just only plug in the power adapter.
Do any lights on the laptop light up when you power it on? Does it beep?Does it make a sound? Is where you plug your power adapter to your laptop loose or broken?

if no sound or light the its either power adapter , dc jack or cable, or system board .

Please note, it is also a good measure to re seat the memory.
You may need to locate your disassembly guide