I have a Compaq Presario 2100 notebook

hi

does the laptop get power but not turn on?

it could be the power switch on the laptop or the ac adapter

it will need to be checked by a computer technician ask for a quote

cheers

Here's what you can try.
1. Remove the battery and try turning the laptop just from AC adapter. Maybe the battery is bad and shorting the system.
2. Try turning it on just on battery power (with AC adapter removed). Maybe the AC adapter is bad and shorting the system.
3. Try removing memory modules one by one. Maybe your failure somehow related to memory. Test the laptop with only one memory module installed. Try either one.
If nothing helps, the laptop still turns on and off by itself, most likely this is motherboard related failure.

Motherboard dear or processor problem

CPU/Processor

• Socket: 939
• Supports the following processors:
  • AMD Athlon 64 X2 up to 4800+
  • AMD Athlon 64
  • AMD Sempron

CPU/Processor

• Socket: 939
• Supports the following processors:
  • AMD Athlon 64 X2 up to 4800+
  • AMD Athlon 64
  • AMD Sempron

CPU/Processor

• Socket: 939
• Supports the following processors:
  • AMD Athlon 64 X2 up to 4800+
  • AMD Athlon 64
  • AMD Sempron

Cpu/Processor Type
Socket: 939

• Supports the following processors:
  • AMD Athlon 64 X2 up to 4800+
  • AMD Athlon 64
  • AMD Sempron

Try reseating the LCD cable to the video card. If no change, then you will most likely need a replacement LCD (Roughly $150 on EBay)

The notebook battery may have a defect if it will not power on the notebook and if it will not hold a charge. The battery indicator light on the notebook either does not light or always blinks orange. The notebook operates correctly when connected to the AC adapter.
A battery that will not charge may be the result of an AC adapter failure, a system board failure, or a battery failure. Perform the steps below to diagnose the failure.
Troubleshoot the power supply
To verify that the AC power supply is functioning properly, follow the steps below.

1.
Plug the AC adapter directly into a functioning wall outlet, and plug connector into the computer. Do not plug into a power strip, surge protector or secondary power source.
2.
Verify the following operation and take the appropriate action:
*
That all power cord connections are secure.
If the AC adapter connection to the notebook is loose, the connector may be damaged and require repair. Contact HP service and support for further assistance.
*
That the power button or power LED is lit when the computer is on.
*
That an LED on the AC power supply adapter is lit when plugged into an AC wall outlet (not available on all AC power supply adapters).
*
That the AC power supply adapter is the correct type.
Different notebook models require different AC power supply adapters. You will need to know the Product Number of your notebook to determine the Part Number of the replacement part. Click Start > HP Help & Support to view the product name, product number, and serial number that you'll need to have to speak with HP Customer Service.
View the See Also section for information about locating HP Help & Support in your operating system.

Troubleshoot the System Board
If you've verified that the AC power functions properly, troubleshoot the PC's system board by following the steps below.

1.
Remove the battery, and keep the notebook connected to AC power.
2.
Press and release the Power button to start the computer.
*
If the notebook PC powers on , then the AC adapter and system board are functioning properly. Go to Troubleshoot the battery .
*
If the Power LED is off , then the AC power adapter needs to be replaced. Contact HP Service and Support for further assistance.
*
If the power LED is on , but the notebook PC does not power on, then the notebook PC needs to be repaired. Contact HP Service and Support for further assistance.
3.
Shut down Windows by selecting Shut Down from the Start Menu.

Troubleshoot the battery
If you have verified the AC power supply and system board are functioning correctly, troubleshoot the battery by following the steps below.

1.
Insert the battery into the battery compartment on the bottom of the notebook PC.
2.
Connect the AC power supply and allow the battery to charge for 15 to 30 minutes.
NOTE: The Battery Charging light should be on while the battery is charging. If it is not on, check the AC power adapter connection to the notebook PC.
3.
Unplug the AC power adapter cord from the notebook PC.
4.
Press and release the Power button to start the computer using only the battery as the power source.
*
If the PC does not power on, then the battery needs to be replaced. Contact HP service and support for further assistance.
*
If the notebook PC does power on, the battery is functioning properly.
NOTE: If you have purchased a second battery for your notebook PC or you have access to an identical battery, you can also check the battery by inserting the second battery into the PC and performing the Troubleshoot the battery steps again.

http://h10025.www1.hp.com/ewfrf/wc/softwareList?os=228&lc=en&dlc=en&cc=us&lang=en&product=442915

this link is for
Compaq Presario R3000 (AMD) Notebook PC
http://h10025.www1.hp.com/ewfrf/wc/softwareList?os=228&lc=en&dlc=en&cc=us&product=385190&lang=en

this link is for
Compaq Presario 2100 Notebook PC (AMD)

Hi,

There are two (2) different Compaq Presario 2100, 1 is an Intel based and theother is AMD based, which one do you have?

In any case if your OS is WinXP, for Intel pls try here while for an AMD. pls try here.

Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards. Thank you for using FixYa.

try draining the power by removing the ac adapter and battery and press and hold the power button for 10-15 secs then try again. if this doesnt works, then replace the keyboard.

hope this helps!

Karlox

Here you go
All you need is here.
http://h10032.www1.hp.com/ctg/Manual/c00246219.pdf