When the power button of a Samsung Galaxy smartphone breaks, the device often seems like a lost cause once the battery runs empty or it turns off. A frustrating detail: Without a working power button, the device often shows no charging animation when plugged in, but rather stays on a black screen—it appears “dead” even though the battery is charging.

This guide demonstrates a reliable workaround: We force the device into Download Mode using a button combination and use the open-source tool Heimdall on Linux to force a reboot.

ℹ️ COMPATIBILITY

This guide was specifically verified with a Samsung Galaxy M51. However, the method works with almost all Samsung devices that have physical volume keys due to the underlying technology:

  • Galaxy S-Series (e.g., S7 to S21)
  • Galaxy A-Series (e.g., A51, A52, A21s)
  • Galaxy M-Series
  • Galaxy Tab Tablets

Changelog

DateChange
2025-12-09Update & Refinement: Updated to Heimdall 2.2.2, added troubleshooting section, and clarified distinction between Warning Screen and Download Mode.
2025-12-08Initial Version: Guide created based on successful tests with a Samsung Galaxy M51.

1. Prerequisites

Before we begin, ensure you have access to a Linux PC. This guide specifically references Arch Linux, but the commands are easily transferable to Debian/Ubuntu.

⚠️ IMPORTANT: ROOT & BATTERY
  1. No Root on Phone needed: Your smartphone does not need to be rooted. We only need sudo rights on the PC to access the USB interface.
  2. Charge Battery: Ensure the device has been on the charger for at least 15 minutes, even if the display remained black.
  3. Data Cable: Use a fully functional USB data cable, not a charge-only cable.

2. Forcing Download Mode

Since the power button is non-functional, we utilize a service button combination. This step is performed while the device is powered off.

  1. Disconnect Cable: Ensure the USB cable is not connected to the smartphone (but is already plugged into the PC).
  2. Hold Buttons: Press and hold both Volume Up (Vol+) and Volume Down (Vol-) simultaneously.
  3. Connect: While holding both buttons, plug the USB cable into the smartphone.

The display should now light up and show a turquoise Warning Screen (Warning! A custom OS can cause...).

Note: This is not Download Mode yet.

  1. Confirm: Now press the Vol Up key once. Only now does the device switch to the actual Download Mode. The screen will display a large “Downloading…”.

3. Heimdall Setup

We use the tool heimdall, an open-source alternative to Samsung’s Odin.

3.1. Installation

On Arch Linux, install the package as follows (tested with version 2.2.2):

sudo pacman -S heimdall

For Debian/Ubuntu users, the command is usually sudo apt install heimdall-flash.

3.2. Verify Connection

Check if your PC recognizes the smartphone in Download Mode.

heimdall detect

The expected output should be:

Device detected

(If an error occurs here, see Section 5 “Troubleshooting”.)

4. Triggering the Reboot

Now for the crucial step. We send a command to the smartphone that usually cleanly terminates a flashing session.

Run the following command in your terminal:

sudo heimdall close-pc-screen

The Result

You should see a success message in the terminal:

Attempting to close connect to pc screen...
Rebooting device...
Attempt complete

The smartphone screen will immediately turn black and restart. Since we are no longer in the special maintenance mode, the Android system will boot up normally—without needing the power button.

5. Troubleshooting

If it doesn’t work right away, here are the common pitfalls:

Problem: heimdall detect shows “Failed to detect compatible device”

  • Solution A (Cable): The most common issue is low-quality USB cables. Try a different one, ideally the original Samsung cable.
  • Solution B (Permissions): Missing udev rules might be the cause. Try running the command with admin privileges: sudo heimdall detect.

Problem: libusb error or Claiming interface failed

  • Solution: Another process is blocking the USB port. Unplug the cable, wait 5 seconds, and plug it back in. Ensure no other software (like ModemManager) is trying to access the device.

Problem: Device reboots back into Download Mode

  • Solution: In rare cases, one of the volume buttons might be stuck physically. Ensure the keys are not jammed.

6. Technical Background

Why does this work?

  • Hardware Design: Samsung devices have a hardware trigger (Vol+ & Vol- + USB Insert) that activates before the main bootloader. This allows technicians to access the device even with corrupted software or broken physical buttons.
  • The Protocol: The command close-pc-screen sends a specific End-of-Session command to the bootloader. The bootloader interprets this as “Maintenance successfully finished” and initiates a regular system reboot.

📦HEIMDALL SOURCE CODE 📚ARCH WIKI: HEIMDALL