Try unplugging the computer. Let the battery run down 100%. Recharge. See what happens. Edit: If you feel comfortable opening the laptop, remove the battery. Hold the start button for about 15 seconds, then reinstall the battery. Reassemble computer cover. Try restarting the computer. Good luck.

@idyung2unechi for your Dell Latitude 5500 the 3,5 blink codes is indicative of a Power Rail Failure. That means potentially something on your motherboard has failed. To help you further, we really would need to see your motherboard (both sides) and we would need to know what model your motherboard is. · It is possible that this is caused by a bad AC adapter etc. Try this first. Disconnect the power from the computer by unplugging the power cord from your computer. Disconnect all external devices from the computer. Remove the battery Now hold the power button depressed for about 30sec-1min. Reapply the AC power adapter and see if your computer does show any sign of life. · Then do this First you want to check your power supply. Make sure it has the proper voltages. Check to make sure that connectors are not bend etc. Check the DC-in jack of your laptop. Make sure there is no corrosion, debris etc. that prevents it from working · To work on your laptop, use this · Dell Latitude 5500 manual. Check page 131 about using the Build -in-self-test (BIST). Let us know what you find out.

Try removing the laptop battery, unplug the cable, and press the power button. This should discharge any residual charge. Next, try plugging in JUST the power cable and see if the laptop will boot with no battery. If it does, try putting the battery in and see if windows reports charging. (it might take a minute or 2)

The battery is bad and must be replaced.

Hi everyone, If your Dell laptop won’t power on and you notice the white LED lights up for a second and then turns off, here’s what it means and what you can try.What Does This Indicate?This usually points to a power-related issue, it could be the adapter, battery, DC jack, or in some cases, the motherboard. Troubleshooting Steps Try these steps in order: Perform a Hard Reset Disconnect the AC adapter and remove the battery (if removable). Press and hold the power button for 30 seconds to drain residual power. Reconnect the battery and adapter, then try powering on. Check the Power Adapter Ensure the adapter light is on and stable. If possible, test with another Dell-compatible adapter. Inspect the Charging Port Make sure it’s clean and free of debris. A damaged DC jack can prevent proper charging. Run Built-in Diagnostics If the system powers on briefly, tap F12 at startup and select Diagnostics. If you only get a white screen when holding D during power-on, that’s the LCD test, which means the display works. Reset BIOS (if accessible) Enter BIOS (F2 or F12 at startup) and load default settings. If you can’t access BIOS, skip this step. Check RAM Reseat or test RAM modules one at a time. Refer to this video for a visual walkthrough:  No Power Troubleshooting Next Steps – If none of the above worked: If your product is under warranty:Click the Get Help Now button at the bottom-right corner of this page to chat with Dell Tech Support for immediate assistance. If out of warranty:The issue may be with the motherboard or charging circuit, which requires professional repair.