I have a Dell Latitude C600 series. It was working fine then when I went to reboot it the it will not trn on. The battery charge light comes on for awhile but nothing else. I have tried various things i.e. swapped RAM etc down charge for 1 minute etc. Can you help?

Maybe the AC adapter is dead.
It’s possible, the battery light turns on for a moment because the battery has no charge and the AC adapter is dead.
Can you test your laptop with another known good AC adapter?

Thank you for this wonderful site! A suggestion: It would be wonderfully helpful to add a How To Solder the USB port tutorial to this addition. I will keep searching…

You can use this guide:
http://www.laptoprepair101.com/laptop/2007/12/06/dc-power-jack-repair-guide/

The guide explains how to replace the failed power jack, but you can use same technique for replacing the USB port.

I then just tried to start in Safe Mode with just the battery, it worked fine, until the second I plugged in the AC Adapter. At this point it only works on the battery or in Safe Mode if the AC Adpater is plugged in when I start up the computer.

I have a Toshiba Satellite A205, the issue of my laptop shutting off when the ac adapter is plugged in just started happening, but I found that if I keep the laptop in safe mode it won’t happen. Does this still reflect a motherboard problem?

Yes, it’s possible.
Is it shutting off as soon as you plug the AC adapter?
What if you turn off the laptop, remove the battery and try turning it on connected to the AC adapter? Will it start?

My compaq presario v3000 has woobly screen. I tried to mend it by opening it up but I couldn,t open it and access it,s problem region.

You should download the maintenance and service guide (click on the link) for Compaq Presario v3000 notebooks. This is a 7MB pdf file and might take some time to download if you has slow connection.
There are notebook disassembly instructions in the manual. Go to the removal and replacement procedure chapter.

And also the screen is flickering at low angles.

You’ll have to check connections between the video cable and LCD screen, motherboard, inverter board. Could be just connection related issue.
Also, there is a chance that you have a faulty video cable.

When the laptop is turned on, the screen remains completely black/blank and the cooling fan not working.

dell xps m1210

Did you have a chance to test the laptop with an external monitor attached to the VGA port? Can you get video on the external monitor?

First of all, I would check memory modules. It’s possible that one of the modules failed.
1. Try reconnecting memory modules. Remove them from the motherboard and install back in.
2. Test your laptop with each module installed separately. If one of them is faulty, the laptop will start when the bad module is removed.