I faced this problem few days back. I fell asleep while using my Dell Inspiron 6400 on the bed. After a couple of hours, I woke-up, realized it and put it in stand-by mode. In the morning, I tried to turn-on the system but it wouldn't come out of stand-by mode. So, I did a forced shut-down by holding power-button. Since then, the laptop is not booting-up.
Here are the symptoms:
1) When I try to turn it on, the three LEDs caps-lock, num-lock, etc. lit-up for few seconds.
2) The HDD and optical drive get the power.
3) Then the whole system dies down.
4) Only the power status LED is lit.
5) There is life in HDD and optical drive as I can pull out optical drive by pushing its eject button. Similarly, when I turn-off the system, I can hear the HDD power-off sound.
Things that I have tried:
1) Remove one of the two DDR2 RAMs. Swap them. Clean the gold pins with pencil eraser for possible corrosion. When I remove both the RAMs, I get caps-lock and the other LED blinking showing that there is a hardware fault.
2) Remove the HDD, remove the optical drive
3) Open up the laptop and clean the CPU fan and cooling assembly.
4) Reseating the processor.
5) Taking out the battery, AC power and keep power-button pressed for 60 sec to completely drain the residual power. Then putting back the whole assembly.
Overall, there is no result.
I could think of two possible answers: 1) Either both the RAMs are fried 2) The BIOS has been corrupted somehow as the system enters it but cannot proceed further.
A helpful suggestion would be much appreciated....