Troubleshoot your device showing an exclamation mark on a black screen:
This screen is called recovery mode, and it is where an Android device provides options to help repair or install operating systems. Pressing or holding certain buttons during start up will bring up this menu, from the bootloader menu. Most Android devices use the volume up and volume down keys to navigate the bootloader and recovery menu, and they use the power key to select options.
The most common reason for devices starting up in recovery mode is that the device is rooted or has installed a custom ROM. T-Mobile does not provide any support for rooted devices or modified software, and you must refer to the device manufacturer for additional troubleshooting.
If you need help with doing any step, visit the Devices page, select your device, and find the steps.
To fix this issue:
- Remove the battery from your device, and wait five seconds.
If your device battery is not removable, hold down the power button on your device until it completely powers down.
- Re-insert the battery, and turn on the device again.
- If recovery mode appears again, hold the volume up button and then press the power button. Use the volume up or volume down to highlight Reboot system and then press the power button to select it.
- Test if your device shows this error again. Continue to the next troubleshooting step if you still have the problem.
- Perform a master reset on your device.
- If these steps do not work, contact your device's manufacturer.