Red light on computer dell 6400

SOURCE: dell inspiron 6400 touchpad and keyboard work

sounds like your main battery needs replacing,move your mouse over the battery icon in the system tray(by the clock),to see if the battery is charging. If it is battery needs replacing. This can cause all kinds of strange issues .

SOURCE: 3 lights o right hand side of laptop what do they mean

The user manual will supply an in-depth explanation of the led-indicators, aswell as there are normally small icons assigned to each light, sometimes engraved in the plastics, normal lights to be active at average usage are the Power led indicator, will glow as long as device is turned on, the Wireless led indicator will glow when the wireless network module is active, the CPU led indicator will flash occasionally when system is idle, and rapidly when system is active under load, and the Battery led indicator will be active when device is running on battery power. When device goes into sleep or hibernate mode the sleep led indicator might continuously glow or slowly switch on & off varying between systems.

SOURCE: my dell inspiron 6400 won't

The following troubleshooting guidelines are basic troubleshooting steps. Battery Charging It is recommended to charge the battery while the system is off for faster charge times. Users may notice longer charge times when the system is powered on and running graphics extensive applications.
No POST If the system does not perform a Power On Self Test, there are various things to look for:

1. Check to ensure that the system has a power light.
2. If the system has no power light, ensure that it is plugged into AC power. Remove the battery.
3. If the system has power but is not performing a POST, check to see if the keyboard status lights flash to indicate a successful POST, but no video, or that the keyboard status lights are lit in a sequence indicating a system problem.

1. With the power off and the system unplugged, remove all CRUs from the system and reconnect that AC adapter to the system and try again.
2. Run the On Board Diagnostics (OBD).

1. If the LCD is not displaying video or the video is garbled, run the BIST Test.
2. If the LCD is not displaying any video, connect an external monitor to eliminate a no POST problem. A good image on the external monitor eliminates a video card problem or a POST problem.
3. Connect an external monitor when possible for all LCD related problems, to help eliminate a software possibility or video card problem.
4. If the LCD has extremely dim video, attempt to adjust the brightness or connect an AC adapter to eliminate a power management conservation setting set in the BIOS.
5. If the LCD has lines on the screen, check the system during POST as well as system setup to verify if the lines are present in all modes of operation. Run the BIST Utility.
6. If the LCD has color problems, run the BIST Utility.
7. Run the On Board Diagnostics (OBD).

SOURCE: Dell Inspiron 6400 - manually flash BIOS

I just went through this myself - you can fix it, but you need access to another PC to do so.

Start by downloading the latest BIOS update from the Dell website, then open a command prompt and execute the BIOS update file with the -writehdrfile parameter - in my case, the command was:
mm061a17.exe -writehdrfile
This should create a file with the name "mm061a17.hdr" - copy this to a FAT16 formatted USB stick and plug it into one of the USB ports on the laptop. Remove the battery and AC adapter cable.
Then hold down the 'END' key on the keyboard and plug the AC cable back in - the power light should come on. Finally release the 'END' key and the system should start to read the USB stick, reflash the BIOS and finally reboot.