Pull the main battery, then hold the power button for about 30 seconds. That works for some Dell models.
The RTC battery (not CMOS anymore, just powers the clock) is prob on the back side of the mobo.
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== Update ==
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Ok...just thought of something else. Is there a button on your battery with four or five LEDs? It'll be one of those soft membrane buttons. A fully charged battery will light all the LEDs lit for a moment when you press the button. One light is a discharged battery. Flashing lights: battery is deceased and needs recycled. A deceased battery can sometimes prevent the laptop from running, even with a good charger.
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Is your charger working properly? Should be ~19V between the outer part of the plug (ground) and the inner ring of the connector. (don't mess with the pin, it's not relevant now) Can you try a different charger?
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What often happens when the battery is dead due to a bad charger...it has just enough power to get the boot started then it runs out of juice, giving the symptom you're seeing.
Pull the main battery, then hold the power button for about 30 seconds. That works for some Dell models.
The RTC battery (not CMOS anymore, just powers the clock) is prob on the back side of the mobo.