Dell laptops have issues with the power regulation chip. What you need to do is pull the back cover off and unplug both the main battery and the CMOS battery. You need to be very very careful removing the CMOS battery. Do not pull the battery out by the wires. I find it’s best to use a plastic pry tool of some form, whether it be a spudger, old credit card or some other thin semi-semi blunt plastic tool. If you rock the two sides back and forth then push out the connector down the center, it will come out. The CMOS battery looks like this: https://guide-images.cdn.ifixit.com/igi/rWTpWLLvSdZ36TQU.large Once you have both batteries unplugged, hold the power button for 60 seconds. Yes, really, 60 seconds. Plug both batteries back in and plug in the charger, then attempt to turn the laptop on. If all went well, the CPU fan should spin over a few times before the machine finally boots back up. Put the cover back on and you’re done. Source: I’ve been working in IT Support/Management with Dell as our main vendor for the last 12 years.

Try unplugging the charger > Press & Hold the power button for 30 seconds > Plug the charger back in and attempt to boot.

@RiderSide​ No, plugged with original charger, nothing else... this is just another Dell mistake that will cost us the customers time and money.

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.

Thank for the reply, but as I said, I tried turning the laptop on without the battery. It doesn't help. And I have 2 different chargers (both original dell, one that came with the laptop and a new one that is also 180 w and 19,5 V  and is listed as compatible with my laptop). I even tried different plugs in my house. I would hope the charger or battery would be the issue, but the battery is out and the laptop won't turn on with either of the chargers. I will just bring it to the professionals again and hope that they will actually fix it or at least tell me that it can't be fixed instead of claiming that nothing is wrong. Thank you all for the replies.