I installed a replacement mouse pad and buttons in the 6400. After re assembling the screen stays black and the lights near the power button flash A and down together the 9 comes on and stays on. I have rechecked the the screen turn off button and checked that the black and white wire from it are connected. I've checked that the memory is seated properly. I also tried removing the battery and holding the power button for 60 seconds. I can't seem to find anything else obvious. Any ideas would be most welcome. Thanks.

Hi Jet,

Do you have an external monitor that you could connect the Inspiron to in order to prove if the screen is black due to a bad connection?

With regards to the flashing lights, is this actually normal. I'm guessing that the "9" is the Num Lock light, the "A" is the Caps Lock light and the "down" is the Scroll Lock light. In that case, what you described there sounds normal.

I presume that the black and white wire that you checked is coming out of the bottom of the display panel and plugging into a connector on the motherboard or graphics card?

I can't think of anything else in that area that you could have dislodged .....apart from the keyboard itself. I presume that you had to take that out to remove the palm-rest plastics around the trackpad. Double-check the ribbon cable connector for the keyboard - they can be quite tricky to get the cable in and the connector locked shut.

Let us know how you get on :-)

Thanks for for explaining what the lights represent num lock, caps lock, will try external monitor as you suggest. Also will re check the keyboard ribbon.Do you think that the ribbons on the mouse and buttons are worth re checking as they were quite fiddly to connect. Thanks

Hi Jet,

I would be surprised if a disconnected trackpad cable could cause the symptoms that you've described but, to be honest, I've never changed a trackpad. It wouldn't do any harm to double-check it if you're going to be opening the laptop up again.

However, the flashing lights that you described suggest that the laptop is starting up, or at least getting past the POST (Power-On Self-Test), so I suspect that it's down to the screen. Plugging in an external monitor would prove this.

Another check might be possible: Does your laptop have a hard disk activity LED? This will be similar to the Caps Lock, Num Lock and Scroll Lock lights, although it might be on a different part of the laptop. This LED will normally flicker when the laptop is busy, particularly when it is starting Windows. If you see that LED flickering almost constantly a few seconds after those other LEDs flash, then that suggests that Windows is starting up normally (even if you can't see it happening). If you don't know whether you have a hard disk activity LED, then don't report back that you can't see it because that proves nothing! ;-)

Thanks for your reply sorry I've taken a while to come back. Due to a hectic weekend of grand children and birthdays the first chance I've had to get back to this is today.
I have plugged it into an external monitor and its working OK the mouse and buttons are also working fine. So would this indicate that all the ribbons are connected OK or could there still be a problem with them that would cause the problems with the display or do you think it is the display only I should be looking at. Thanks

Well I'm pleased to say I've had a result. Decided to go ahead and check all the connections back to the screen. The first thing I checked the motherboard connection was loose, I must have caught it when opening up the laptop. Anyhow bingo the screen is now working again and I have a happy wife again.
Many thanks for your help on D-A-l , I don't often get problems but its so helpful to be able to come on this forum and get help and support if needed.