If your Samsung Galaxy S24 is completely black and won't respond when you press the side button, don't panic just yet. A completely dead battery is the most common reason, but there are a few other things you can try before assuming the worst. I'd start with the simplest fix first.
Charge Your Phone Properly
Your S24 might have a battery so drained that it needs a proper wake-up charge. Plug it into a wall outlet using the original USB-C cable and a compatible 25W Samsung charger if you have one. Let it charge, undisturbed, for at least 30 to 45 minutes.
Sometimes the phone won't even show a charging icon if the battery is too low. After that time, press and hold the Volume Down button and the Side button together for about 10 seconds to try a force restart. If you see the Samsung logo, you're back in business.
If it doesn't charge, try a different cable and power adapter. Make sure the USB-C port on your phone is completely clean and free of lint, which can prevent the cable from seating fully.
Perform a Force Restart
This is the equivalent of pulling the plug on a frozen computer and often works when the screen is black. Press and hold the Volume Down button and the Side (power) button simultaneously.
Keep holding them both for about 10 to 15 seconds. You should feel a vibration and see the Samsung logo appear on the screen. This forces a hard reboot without deleting any of your personal data or settings.
It clears out any temporary software glitches that might be preventing the phone from waking up. If the screen stays black and nothing happens after 20 seconds, move on to the next step.
Check for a Moisture Detection Error
The Galaxy S24 is known to sometimes give a false "moisture detected" warning in the USB-C port, which will completely block charging as a safety measure. Even if your phone is off, this error can prevent it from powering on.
If you've recently been in a humid environment or there's any chance of condensation, this could be the culprit. The best fix is to power down the phone completely, if you can, and leave it in a dry, warm place for a few hours.
You can also try gently drying the port with a blast of cool air from a can of compressed air. Avoid using heat or inserting anything like a cotton swab, as you could damage the sensitive pins inside the port.
Inspect Your Charging Gear
Your phone might be fine, but your charger or cable could be the problem. The S24 supports 25W Super Fast Charging, but only with a compatible PPS (Programmable Power Supply) charger, like Samsung's official one.
Try a different USB-C cable and a different power brick altogether. Plug it into a known-good wall outlet, not a computer or a car charger, to ensure it's getting maximum power. Also, if you're using a case, try removing it in case it's preventing the cable from plugging in all the way.
Wireless charging is another good test. Place your S24 on a Qi wireless charger. If it begins charging wirelessly, you know the battery and phone are functional, and the issue is isolated to the USB-C port or your wired cable.
Boot Into Safe Mode
If your phone turns on but gets stuck on the Samsung logo or during startup, a recently installed app might be causing a conflict. Booting into Safe Mode loads the phone with all third-party apps disabled.
First, force restart the phone as described earlier. The moment you see the Samsung logo appear on the screen, release the Side button but keep holding the Volume Down button. Keep holding it until you see "Safe Mode" in the bottom-left corner of the screen.
If the phone boots successfully in Safe Mode, you've confirmed a bad app is the problem. You can then go to Settings > Apps, sort by "Last used," and start uninstalling recent downloads until the phone boots normally.
Check Battery Protection Settings
Your Galaxy S24 has a feature called "Protect battery" that limits maximum charging to 85% to prolong the battery's lifespan. If you were already low on battery and it only charged to 85% before you unplugged it, it might have died faster than you expected.
This isn't a fix for a phone that won't turn on at all, but it's a good setting to know about for the future. You can find it in Settings > Battery and device care > Battery > More battery settings.
If you need every bit of charge for a long day, you can toggle "Protect battery" off. Just remember to turn it back on if you want to keep using the feature for daily battery health.
Wipe the Cache Partition
Corrupted system cache files from an update or an app can prevent the phone from booting properly. Wiping the cache partition in recovery mode clears these temporary files without touching your personal data.
First, connect your phone to a computer with a USB cable. Then, press and hold the Volume Up button and the Side button together. When the Samsung logo appears, release only the Side button but keep holding Volume Up until you see the Android Recovery screen.
Use the Volume Down button to navigate to "Wipe cache partition" and press the Side button to select it. Confirm the action, then select "Reboot system now" when it's done. This process can resolve boot loops after a software update.
Consider a Factory Reset
This is your last resort before seeking repair, as it will erase everything on your phone. You'll need to use the same recovery mode menu mentioned in the previous step.
In the Android Recovery screen, navigate to "Factory data reset" or "Wipe data/factory reset" using the volume keys. Select it with the side key. You will have to confirm this action on the next screen.
The phone will reset and reboot, which can take several minutes. Only try this if you have a recent backup of your data in Samsung Cloud or on your Google account, as there is no way to recover anything after this step.
