I have a Dell Inspiron 9400- used. I do not know what has/may have or haven't happened to it unfortunately:( When I turn on the computer with power button, computer clearly turns on, then the DELL startup page is displayed BRIEFLY (like for a split second only!), then the screen goes blank/black and stays that way. What can I do? If anything. Thanks

There are two possible causes for this issue:
1) Your dell 9400 charger is malfunction
2) Your laptop dc power jack is loose or dead

Possible troubleshooting step:
1) Borrow a compatible dell charger to plug in your laptop, if it works without any issue, it means your dell inspiron 9400 adapter need to be replaced.

2) If the compatible dell 9400 charger won't work normally, the problem may lie in your dc power jack.

Hope this will help.

you may need to change your power settings. it sounds like when you plug it in it goes into a mode thinking there is another monitor hold the FN key and press a key usually f5 that looks like a computer monitory. anyway plug in the pwoer cable, and hold fn and press the key that looks like a computer monitor maybe twice until the monitor comes back on let me know if that works!

try to charge the battery while the computer is off for 3 hours. if that does not work, remove the battery from the computer and turn on the computer using only the ac adapter. if the computer is working fine using only the ac adapter, call your computer manufacturer for possible battery replacement

Dell Laptop with bios or hard drive password set ? Unlock your dell laptop using the link below if it display a message that says "this computer system is protected by a password authentication system, you cannot access the data on this computer without the primary or administrator password, when you turn on the computer. This message is what you get if the BIOS is protected by a password. or you get system disabled

Go to: http://dell-inspiron-9400-bios-password.biospwd.com to get your dell bios password authentication and get full access to your dell computer, they can unlock almost all dell laptop such as dell inspiron, xps, latitude, precision, studio, vostro

Check the power settings. Start/Control Panel/Power Options. There is a setting separate from the screen saver to turn off the screen in the Power Options control panel. DVD playback overrides the power options settings.

If the computer is connected to an electrical outlet, the light operates as follows:

• Solid green: The battery is charging.
  
  
• Flashing green: The battery is almost fully charged.
  
  

If the computer is running on a battery, the light operates as follows:

• Off: The battery is adequately charged (or the computer is turned off).
  
  
• Flashing orange: The battery charge is low.
  
  
• Solid orange: The battery charge is critically low.

Looks like the AC adaptor is faulty.

you may have damaged the screen in which case theres not much more you can do then replace it.if its a new labtop it may be still under warrenty in which case get back to dell.

sounds like bad motherboard/power supply. Just to be sure though have you upgraded the ram? If you have more then one memory chip try siwtching out each one and seeing if it's boot farther. It's possible a dimm went bad or the port it's in went bad. Otherwise motherboard/powersupply

Simply use the external video port. It may require an adapter depending on the monitor you plan to use.

i suggest that you should replace the battery because batterey may be faulty take it down to your nearest pc repair shop