The S6 doesn't have a removable battery, so Samsung included a reset sequence. If the power and volume down buttons are held down for a few seconds, the device goes into "Maintenance Boot Mode". From there, options include booting the device normally, performing a factory reset, booting to safe mode, enabling debugging, and powering off. My phone has never frozen completely, so I have never truly needed to use this feature. However, I have tested it a few times, and it appears to work properly. However, I have some questions and observations.
1. How does this feature actually work? Clearly it cannot be part of a standard piece of phone software; relying on Android to respond appropriately to the reset sequence during a complete hang/freeze would defeat the purpose (right?). Is recognition of this "panic" sequence built into the hardware? Is it somehow part of some piece of software that runs at a lower level than the Android OS? Could this behavior, in theory, be modified or removed through changes to the bootloader or some other software on the phone?
2. The behavior of the reset feature seems odd in some cases. For example, I tried resetting my device during startup. I started holding the buttons a few seconds after the "Galaxy S6" splash screen appeared. As a result, the reset was triggered while the startup animation was being displayed. As usual, the notification LED illuminated blue and appeared to "pulsate" (i.e., gradually cycle between light and dark blue) during the animation. Notably, the light did not stop "pulsating" when the phone entered maintenance mode. It even continued when I chose to "power off" the phone from maintenance mode. The result was that my phone appeared to be powered off (i.e., screen turned off, home + volume down + power --> bootloader, holding power --> normal bootup) but still had the "pulsating" blue notification LED normally only seen during the boot animation. The light returns to normal when the phone is allowed to boot normally. Can anyone give an explanation as to why the phone behaves this way?
Thanks in advance
1. How does this feature actually work? Clearly it cannot be part of a standard piece of phone software; relying on Android to respond appropriately to the reset sequence during a complete hang/freeze would defeat the purpose (right?). Is recognition of this "panic" sequence built into the hardware? Is it somehow part of some piece of software that runs at a lower level than the Android OS? Could this behavior, in theory, be modified or removed through changes to the bootloader or some other software on the phone?
2. The behavior of the reset feature seems odd in some cases. For example, I tried resetting my device during startup. I started holding the buttons a few seconds after the "Galaxy S6" splash screen appeared. As a result, the reset was triggered while the startup animation was being displayed. As usual, the notification LED illuminated blue and appeared to "pulsate" (i.e., gradually cycle between light and dark blue) during the animation. Notably, the light did not stop "pulsating" when the phone entered maintenance mode. It even continued when I chose to "power off" the phone from maintenance mode. The result was that my phone appeared to be powered off (i.e., screen turned off, home + volume down + power --> bootloader, holding power --> normal bootup) but still had the "pulsating" blue notification LED normally only seen during the boot animation. The light returns to normal when the phone is allowed to boot normally. Can anyone give an explanation as to why the phone behaves this way?
Thanks in advance
