Same problem with 5560, usually I do the power button for >10sec thing, but it didnt work that time. Had to open it up and disconnect the battery and it booted normally

Try a hard reset by powering off, removing the battery (if possible), and holding the power button for 30 seconds. Also, try Fn + F8 or Win + P to toggle displays. External display is another option.

Experiencing a no-boot issue with a black screen on your Dell Inspiron laptop can be caused by various factors, including hardware and software problems. Here's a step-by-step guide to help you troubleshoot and potentially resolve the issue: Power Cycle: Start by performing a power cycle. Disconnect the laptop from the power source, remove the battery (if applicable), and hold down the power button for about 15-20 seconds. Reconnect the battery and power adapter, and then try turning on the laptop. Check Power Indicator Lights: When you try to turn on the laptop, observe any power indicator lights. They might provide clues about the status of your laptop's components. External Display: Connect the laptop to an external monitor or TV using the appropriate cable. If the external display shows an image, the issue could be related to the laptop's internal display or its connections. Remove External Devices: Disconnect all external devices like USB drives, printers, and external monitors. Sometimes, a malfunctioning external device can prevent the laptop from booting. RAM Reseating: If the RAM modules are not seated properly, it can cause boot issues. Open the laptop's access panel, remove the RAM modules, and then reinsert them firmly. Hard Drive/SSD Issues: A faulty or corrupted hard drive or SSD can prevent the laptop from booting. Listen for any unusual sounds coming from the laptop's storage area. If you suspect a storage issue, you might need to replace the drive and reinstall the operating system. BIOS/UEFI Reset: Reset the BIOS or UEFI settings to default. Sometimes, incorrect settings can lead to boot problems. Battery Check: If the laptop's battery is faulty or not holding a charge, it could affect the boot process. Try booting the laptop with just the power adapter connected, bypassing the battery. External Bootable Media: Create a bootable USB drive with a recovery or diagnostic tool. Boot your laptop from the USB drive to perform tests and troubleshoot issues. Professional Help: If you've tried the above steps and the issue persists, it might be best to seek help from a professional technician. They can diagnose hardware issues more accurately and perform repairs if needed. Factory Reset/Operating System Reinstall: If all else fails and you're comfortable with it, you could consider performing a factory reset or reinstalling the operating system. This should be a last resort, as it will erase all data on the laptop. Remember that troubleshooting hardware issues can be complex and potentially risky. If your laptop is under warranty, consider reaching out to Dell support for assistance. If not, and you're not comfortable with the steps, it's advisable to consult a professional technician.