When your HP EliteBook 840 won't start, it's a real roadblock. The screen stays black, the fans are silent, and nothing happens when you press the power button. Before you worry about major hardware failure, there's a sequence of checks that can often get you back up and running.
Check Your Power Connection
Start with the basics. Make sure the power adapter is firmly plugged into the wall outlet and the laptop's charging port. I'd also check the LED on the adapter itself, if it has one, to confirm it's getting power. Sometimes, a different wall outlet or power strip can make all the difference if the first one is faulty.
For the EliteBook 840, pay close attention to the connection at the laptop. If you're using a USB-C charger, ensure it's clicked in securely. A loose connection here won't deliver any power, making the laptop appear completely dead.
Perform a Hard Reset
This is a very effective first step for many power issues. Disconnect the charger from the laptop. Hold down the power button for a full 15 seconds. This action drains any residual power from the capacitors and can clear a temporary hardware hang.
After the 15 seconds, plug the charger back in. Wait a moment, then press the power button normally to try and turn it on. You don't need to remove the internal battery on most modern EliteBooks for this to work, as the process achieves the same goal.
Look for Signs of Life
Your laptop might actually be on, but the display isn't working. In a quiet room, listen closely for any fan noise or the faint sound of a spinning drive. Feel the keyboard area for warmth after a minute or check if the Caps Lock or Num Lock keys light up when you press them.
Try connecting an external monitor using the HDMI or USB-C port. If the external display shows your login screen or BIOS, then the issue is isolated to your laptop's internal screen or its connection. This is a crucial diagnostic step.
Test with a Different Charger
If you have access to another compatible HP USB-C charger, try it. The EliteBook 840 typically uses a 65W adapter, but it can often work with other USB-C PD (Power Delivery) chargers, at least to boot. If the laptop springs to life with a different charger, you've found your culprit.
Using underpowered chargers, like those meant for phones, usually won't work for booting, though they might charge the battery slowly when the laptop is off. Stick to a known-good, higher-wattage adapter for testing.
Disconnect Everything from the Laptop
A faulty peripheral can sometimes prevent a laptop from starting. Unplug everything: docking stations, USB drives, external monitors, Ethernet cables, and SD cards. Even a corporate-issued security dongle could be the cause.
With the laptop stripped down to just the power adapter, try turning it on. If it boots, you can reconnect devices one by one to find the problematic piece of hardware. This is a common fix for enterprise setups where many peripherals are used.
Observe the Charging LED
Look for the small LED light near the USB-C charging port or on the front edge of the laptop. When you plug in the adapter, this light should turn on, usually white or amber. If no light comes on at all, the problem is almost certainly with the power source, the charging port, or the motherboard's power circuitry.
If the LED is solid white, it often means the battery is fully charged. A blinking amber light can indicate a battery error. A solid amber light usually means it's charging. Any light is a good sign that the laptop is receiving power.
Let It Charge Undisturbed
If the battery was fully drained to zero, the system might need to sit on the charger for a while before it has enough juice to initiate a boot. Leave it plugged into the original adapter for at least 30 minutes without trying to turn it on.
After this charging period, try the power button again. Some models will show a battery icon on a black screen when recovering from a deep discharge, even before Windows loads.
Access the BIOS or Diagnostics
Try to interrupt the normal boot process to access the underlying hardware menus. Immediately after pressing the power button, repeatedly tap the F10 key to enter the BIOS Setup, or F2 to launch the HP PC Hardware Diagnostics (UEFI).
If you can get into either of these menus, it proves the core hardware (CPU, memory, motherboard) is functional. The problem likely lies with Windows, your drive, or the boot configuration. From here, you can run diagnostics or access recovery tools.
Inspect for Physical Issues
Give the laptop a visual inspection. Look for any signs of liquid damage or obvious physical trauma. Carefully check the bottom case for any unusual bulging, which is a sign of a swollen battery.
A swollen battery is a safety hazard and can physically prevent the laptop from turning on by putting pressure on internal components. If you see any bulging, stop using the laptop and contact IT support or HP for a battery replacement immediately.
Consider Enterprise-Specific Factors
The EliteBook 840 is often deployed in corporate environments, which can introduce unique issues. Conflicts with enterprise security firmware or management software can sometimes block a successful boot. If you have access to HP Support Assistant, it can help manage and validate critical driver and BIOS updates that might resolve stability issues.
Also, remember that HP's Sure Start feature is designed to automatically recover the BIOS if it gets corrupted. If you see a black screen with recovery messages after turning it on, let the process complete. It might take several minutes and a couple of reboots to restore itself.
