If your iPhone 15 is completely black and won't respond, the first thing to try is a force restart. This is different from a normal restart and can clear out temporary software glitches that freeze the phone. Press and quickly release the Volume Up button, then press and quickly release the Volume Down button. Finally, press and hold the Side button until you see the Apple logo appear on the screen.
You'll need to keep holding the Side button for about 10-15 seconds. Don't let go when you see the Apple logo, wait for it to fully appear and the phone to begin its startup sequence. This is the single most effective first step for an unresponsive iPhone 15.
Check Your Charger and Cable
Your iPhone 15 might simply have a dead battery. This model was Apple's first to switch from Lightning to USB-C, so it's crucial you're using a USB-C cable. Plug it into a wall outlet using an Apple USB-C power adapter or a reputable third-party one that supports USB Power Delivery.
Let it charge for at least 30 minutes. If you don't see a charging icon or the red battery symbol after a few minutes, try a different USB-C cable and a different power adapter. I've seen many cases where a faulty cable, even a brand new one, is the culprit. Also, remove any thick or metal phone case, as it can interfere with the connection.
Look for Signs of Life
While it's plugged in, press the Side button once. Look very closely at the screen for any faint glow or a red or green battery icon in the top corner. If you see the battery icon but it won't progress, the charging port might be dirty.
Grab a can of compressed air and gently blow into the USB-C port, or use a dry, soft-bristled brush to dislodge any lint. Never use a metal object like a paperclip. A blocked port is a common reason an iPhone 15 won't charge or turn on.
Understand the 80% Limit Feature
The iPhone 15 has a battery health feature called "Charging Optimization." One of the options is an 80% Limit, which stops charging before the battery is full to prolong its lifespan. If this is enabled, your phone might stop showing a charging icon at 80%, which can be mistaken for a problem.
Once your phone is on, you can check this in Settings > Battery > Battery Health & Charging. For now, if the phone is off, just be aware that it may take longer to reach a charge level high enough to power on if this setting was active.
Try a Computer Connection
If a wall outlet isn't working, connect your iPhone 15 to a computer's USB-C port using your cable. Make sure the computer is powered on and not in sleep mode. A direct connection to a Mac or a Windows PC with a powered USB port can sometimes provide a more stable trickle charge to a deeply drained battery.
Listen for the connection chime on a Mac or check for the device in Windows Explorer. If the computer recognizes it but the screen stays black, the issue is likely with the iPhone's display or logic board, not the battery.
Check for Overheating
The iPhone 15 can get warm during fast charging, especially with MagSafe or certain cases. If it overheats, it will stop charging entirely to protect the battery. Unplug the phone and remove it from any wireless charger.
Let it cool down in a shaded, room-temperature spot for at least 30 minutes. Then, try charging it again without a case on. Using a standard 20W USB-C charger instead of a 27W or 15W MagSafe charger can generate less heat for this initial recovery charge.
Use Recovery Mode
If the force restart did nothing and the phone is still unresponsive after a long charge, you may need to use recovery mode. This requires a computer with the latest version of Finder (on Mac) or iTunes (on Windows).
Connect your iPhone 15 to the computer with a USB-C cable. Quickly press and release the Volume Up button, then the Volume Down button. Then, press and hold the Side button. Keep holding it even after the Apple logo appears, until you see the recovery mode screen on your iPhone (a cable pointing to a computer icon).
Your computer will then give you the option to Update or Restore. Choose Update first, as it will reinstall iOS without erasing your data. This can fix deeper software corruption preventing a normal boot.
Consider a DFU Restore
DFU (Device Firmware Update) mode is a deeper restore than recovery mode. It's the last software step before assuming a hardware fault. The button sequence is very specific and timing is key.
With the phone connected to the computer, press and release Volume Up, then Volume Down. Now, press and hold the Side button for 10 seconds. After 10 seconds, without letting go of the Side button, also press and hold the Volume Down button for 5 seconds. Then, release the Side button but keep holding the Volume Down button for another 10 seconds. If the screen stays completely black, the computer should detect a device in recovery mode. You can then initiate a restore through Finder or iTunes, which will erase all data and install a fresh copy of iOS.
