I have a Dell Inspiron 1150 which had a problem with the plug (solder cracked through normal use). I bought a new part, desoldered the old one, soldered in the new one, and put everything back together. Unfortunately, now the laptop won't start.

The symptoms are:
Power Light comes on.
Fan comes on for a while, then shuts down.
Screen is blank.
There are no warning beeps or blinks.
Power light stays on until the power button is pressed to turn the computer off

Things I have tried:
1) Powering up with only the power cord, and no battery
(same symptoms)

2) Powering up with the battery in, with or without the power cord
Above symptoms, plus:
Hard Drive light blinks yellow four times, green once, and repeats
(This usually indicates a bad battery. I don't think it is related.)

3) Removing hard drive, CD drive, and network card
(same symptoms)

4) Rearranging or removing RAM
(same symptoms)

5) Disconnecting the keyboard and touchpad cables
(same symptoms)

6) Removing LCD screen, stripping down to motherboard, and attaching external monitor
(same symptoms)

Just wondering if anyone can think of anything else I could try.

I did notice one thing that seems odd to me, but I am not experienced with working on laptops (mostly just desktops). If I look closely at the CPU, I can just barely see the top of the pins (the CPU is not seated all the way down flush in the socket). I tried removing it, repositioning it, etc, but no matter what I do, that is as far as it seems to go. It is glued to the heat sink, which has screws designed to prevent them from being screwed down any further, so I can't apply pressure directly to the CPU to see if it will go in further. I may try removing the heat sink and see if I can get the CPU to go down more flush, then clean and reapply thermal greese. If any of you are familiar with the Inspiron 1150, do you happen to know if the CPU is supposed to be perfectly flush or not?

I ordered a miniPCI POST card diagnostic tool, which might help me learn if there is something wrong with the motherboard. I will be sure to post if I manage to figure this problem out for myself.