What does Bootloader do? - EVO 4G Q&A, Help & Troubleshooting

I have a custom built Rom on my Evo and I have what may be considered as a stupid question. When I go to reboot and it gives the list of options, I noticed an option called bootloader. I was just curious as to what it does?
Can anyone help?
J-Weezy

Boot loader is like the bios screen on the computer.
You can do certain functions from it such as flashing. The bootloader functions can be considered as a sort of last resort. Most flashing is done through the recovery program (similar to a hard drive imaging program). If you can't boot into the boot loader and your recovery is hosed, your chances of debricking the device are slim

Thanks a lot. My recovery works just fine. I guess I really don't have to worry about it.
Sent from my PC36100 using XDA App

Related

Frozen Bootloader...

I have a XDA that will not boot furthur than initializing the ROM version, radio stack and the G324e4 at the bottom right of the screen. I have tried to load a bootloader via sd from another XDA and have tried running the XDA tools bootloader app with no success. Does anyone have an idea on how i can fix this? I have been following these threads for a long time now and have become an experienced user. With this XDA, Im really willing to try anything to get it booting correctly. Thanks in advance. -Justin
I forgot to mention that the bootloader does work normally otherwise, all options are fuctional and the ROM is flashable. It just wont fully boot up.

Phone gets stuck on bootloader?

Ok all,
I'm a dev. I compile kernels, AOSP, cook roms, etc. Which is why I feel so stupid lol Whenever I try to boot into recovery from my phone I hold in the power and vol down keys. This loads up the bootloader and then I reboot into recovery from that menu. This worked for the longest time. Now however, whenever I try this it stalls when it checks for PC36DIAG.zip, the first one it looks for. I don't understand why. Whenever I try to do adb shell reboot recovery it works flawlessly. But it would be useful to boot into recovery without a pc or adb. Any ideas why this is happening?
Same thing happens with me and its annoying I agree. I don't know why it checks for that image each time:/
Sent from my PC36100 using XDA App
imaxreed said:
Same thing happens with me and its annoying I agree. I don't know why it checks for that image each time:/
Sent from my PC36100 using XDA App
Click to expand...
Click to collapse
I know why it checks for that image. It checks for a number of them. HTC's bootloader checks to see if those images are on the sd card so you can flash them. It's how the RUUs work. Thing is it's supposed to check and if the zip file doesn't exist it's supposed to move on to the next one. Unfortunately this doesn't happen. I'm wondering, is it the engineering bootloader we flashed? Maybe there's a bug in it?

New SGS3 possible hard brick! PLEASE HELP

Heres one for you all. Just got my GS3. Rooted it..bla bla..bla. Was running on stock rom of course and decided to try out one of the cm10 nightlies. Did my back up..bla bla bla and new rom would not flash. tried another and got the same thing. I was reading around and came across someone asking another guy if he had unlocked his bootloader because the same thing was happening to him.. The guy provided the .apk to unlock bootloader so I figured Id try it. Unlocked fine. Went to Rom Manager and booted into recovery.
Thats the last time my phone has been on. I cant get to anything. I can plug it into computer and hold power, vol, home buttons down for download mode and recovery but nothing. The computer will beep like its acknowledging it but still doesn't do anything. PLEASE HELP. This is my first Samsung and Ive always been able to get to recovery or bootloader to fastboot but this has me completely shut out. Im desperate. Thanks.
EDIT: remember, I never got to flash a new rom. All I did was use that unlocker.apk(not sure of the name) to unlock then booted into recovery from rom manager. Using that unlocker i believe is what did it. Like I said, im new to samsung, besides rooting some s2's for people at work and never had to unlock bootloader on their S2's
Unlocker.apk? Maybe it's a good thing I don't know what that is? But I would guess that may be part of your issue .
How did you get root?
Did you use this http://forum.xda-developers.com/showthread.php?p=28019751 ???
Sent from my SAMSUNG-SGH-I747 using xda premium
Unlocker.Apk? Never heard of that and the at&t gs3 doesn't even have a locked bootloader. What user gave you that? If you can get into download mode.. (power off phone ..hold volume down + power button + home button) then flash back to stock.
I see that you CAN get into recovery? Since you made a backup ...why not just use it?
Sent from my SAMSUNG-SGH-I747 using xda premium
Assuming you're running the AT&T version, your bootloader was never locked. So, running an app to unlock your bootloader (which would be for a different phone), seems like a sure-fire ticket to brick town.
Seeing as how you can't boot into recovery or download mode at the moment, I would imagine your only recourse would be to try a USB jig to get into download mode to try to flash back to stock. Else, if the jig doesn't get you into download mode you'll either have to seek out JTAG service, try to get a replacement via warranty (make up some story), or enjoy your new paperweight and buy a new phone.
Good luck.
defnow said:
Unlocker.Apk? Never heard of that and the at&t gs3 doesn't even have a locked bootloader. What user gave you that? If you can get into download mode.. (power off phone ..hold volume down + power button + home button) then flash back to stock.
I see that you CAN get into recovery? Since you made a backup ...why not just use it?
Sent from my SAMSUNG-SGH-I747 using xda premium
Click to expand...
Click to collapse
I too have never heard of this apk. It sounds malicious. He should return to stock. One time after rebooting my phone the Rom would never boot; the screen was black. I even tried restoring a backup but that yielded the same results. Get into Odin and flash a stock package from the dev thread.
Sent from my SAMSUNG-SGH-I747 using Tapatalk 2
If you need JTAG this guy who posted this thread evidently had good luck. Check it out.
http://forum.xda-developers.com/showthread.php?p=30942252
Sent from my SAMSUNG-SGH-I747 using xda premium
Have you tried...
There really aren't enough details in your initial post to properly speculate on what is happening or happened with your phone, but...
I found that the easiest way to enter Recovery and Download mode is when the phone is not connected via USB.
Have you tried entering Download mode while the phone is not plugged in via USB?
Unlocker.apk meant for the Verizon s3?
Yeah..
Congratulations on your shiny new paperweight!
JTag is your only hope.
Goodluck!

Recovery protection possible??

Hi,
i just had an Idea about the security of your devices. So i think i can say that nearly everybody here has an recovery installed and some of us my use a screen lock. But if you have it or not it doesn't matter, because you can simply install a new rom via recovery and the tief can use your phone as it was his. Also most of us have debugging activatet. So you also can hack the phone with adb. Last one you can simply deactivate if you are not a modder. But the recovery is still open. So my question is is it possible to make a password, patter, or something like this at the start of the recovery??
Any Ideas??
HandyBesitzer said:
Hi,
i just had an Idea about the security of your devices. So i think i can say that nearly everybody here has an recovery installed and some of us my use a screen lock. But if you have it or not it doesn't matter, because you can simply install a new rom via recovery and the tief can use your phone as it was his. Also most of us have debugging activatet. So you also can hack the phone with adb. Last one you can simply deactivate if you are not a modder. But the recovery is still open. So my question is is it possible to make a password, patter, or something like this at the start of the recovery??
Any Ideas??
Click to expand...
Click to collapse
thats a good idea but kinda pointless im afraid. if ur phone is stolen and the person knows how to enter recovery to re flash a rom then id say they will probably know that they can simply boot into fastboot, flash Alpharev downgrader then run a ruu, or flash recovery to overwrite the one u have

Bricked nexus 7 won't even charge

So I tried using the wugfresh toolkit last nigh to root since from what I've read all the nexus devices use the same method to unlock the bootloader and such. This was likely a mistake. After figuring out I had to change the device to PtP I managed to get to the unlock bootloader screen on the device, at which point it became unresponsive. I turned it off completely, and at that point it wouldn't boot at all, it would just sit on the nexus logo forever. I also couldn't fastboot, holding down the power, volume up and volume down buttons seemed to do nothing. So I let it run down last night in hopes of starting on a fresh charge. Now the device doesn't seem to want to charge at all. I plugged it into both my computer and wall charger through the usual usb cable, and the screen isn't showing any indication of charging. All I saw was the notification light blinking in short bursts after initially plugging it in, and now not even that is happening.
Ideas?
Reboot to recovery and wipe dalvik, cache and system and reboot
Sent from my Nexus 7 using xda premium
Simer03 said:
Reboot to recovery and wipe dalvik, cache and system and reboot
Sent from my Nexus 7 using xda premium
Click to expand...
Click to collapse
If you wipe system, what exactly are you expecting to reboot into???
je
Simer03 said:
Reboot to recovery and wipe dalvik, cache and system and reboot
Sent from my Nexus 7 using xda premium
Click to expand...
Click to collapse
Exactly....I can't reboot into recovery because I can't fastboot into anything. I'm not sure how this helps.
destructobob said:
Exactly....I can't reboot into recovery because I can't fastboot into anything. I'm not sure how this helps.
Click to expand...
Click to collapse
A few points.
First, this is why I highly discourage 'toolkits', especially on Nexus devices. There simply is no reason to use them and many reasons not. It is much wiser to learn how to do things manually, as it makes troubleshooting problems much easier and is less likely to cause a problem. For example, to unlock the bootloader, you could have issued a single command to accomplish it.
Second, as I don't use toolkits, I can't say exactly how the one you used works, but it most likely automates that 'fastboot oem unlock' command, which IS the same for both N7 versions. If so, it shouldn't have caused you any issues.
Third, assuming all you did was attempt to unlock the bootloader - and not flash any custom stuff, root the device, etc. - you should not be running into this issue. If you did try something else, that could certainly explain some of the problems you have. There is certainly a possibility that your device is defective. It it truly won't charge or function at all, I would highly recommend you return it for a new one. If it's dead, there should be no reason why they won't take it back.
Next time, I would recommend doing things the old fashioned way .
phonic said:
A few points.
First, this is why I highly discourage 'toolkits', especially on Nexus devices. There simply is no reason to use them and many reasons not. It is much wiser to learn how to do things manually, as it makes troubleshooting problems much easier and is less likely to cause a problem. For example, to unlock the bootloader, you could have issued a single command to accomplish it.
Second, as I don't use toolkits, I can't say exactly how the one you used works, but it most likely automates that 'fastboot oem unlock' command, which IS the same for both N7 versions. If so, it shouldn't have caused you any issues.
Third, assuming all you did was attempt to unlock the bootloader - and not flash any custom stuff, root the device, etc. - you should not be running into this issue. If you did try something else, that could certainly explain some of the problems you have. There is certainly a possibility that your device is defective. It it truly won't charge or function at all, I would highly recommend you return it for a new one. If it's dead, there should be no reason why they won't take it back.
Next time, I would recommend doing things the old fashioned way .
Click to expand...
Click to collapse
It turns on, it's on at the moment actually. It's been sitting at the nexus logo for about ten minutes. And I still can't load into fastboot, holding down those three buttons does nothing. I'm not even sure why the device froze at the unlock screen. I'm trying to start up the old fashioned way right now, following this link http://forum.xda-developers.com/showthread.php?t=2379618
I've managed to make my way to the platform tools folder in a command line, but running the reboot bootloader command there does nothing. It simply says device not found. I don't think my computer is even seeing the n7 properly so it can't reboot it. I don't think its defective, but I don't know where to begin to fix this using the old fashioned way either....
phonic said:
A few points.
First, this is why I highly discourage 'toolkits', especially on Nexus devices. There simply is no reason to use them and many reasons not. It is much wiser to learn how to do things manually, as it makes troubleshooting problems much easier and is less likely to cause a problem. For example, to unlock the bootloader, you could have issued a single command to accomplish it.
Second, as I don't use toolkits, I can't say exactly how the one you used works, but it most likely automates that 'fastboot oem unlock' command, which IS the same for both N7 versions. If so, it shouldn't have caused you any issues.
Third, assuming all you did was attempt to unlock the bootloader - and not flash any custom stuff, root the device, etc. - you should not be running into this issue. If you did try something else, that could certainly explain some of the problems you have. There is certainly a possibility that your device is defective. It it truly won't charge or function at all, I would highly recommend you return it for a new one. If it's dead, there should be no reason why they won't take it back.
Next time, I would recommend doing things the old fashioned way .
Click to expand...
Click to collapse
I second all that's been said here. While toolkits can seem attractive, it's really quite simple, and much safer to do it manually once your take an hour to learn your way around the Android-SDK (way easier than it sounds, I promise).
I like toolkits, seriously, but they hardly ever work. I usually have to drop to a shell prompt and run the commands manually anyway.
Sent from Nexus 7 XHD using XDA Premium HD
destructobob said:
It turns on, it's on at the moment actually. It's been sitting at the nexus logo for about ten minutes. And I still can't load into fastboot, holding down those three buttons does nothing. I'm not even sure why the device froze at the unlock screen. I'm trying to start up the old fashioned way right now, following this link http://forum.xda-developers.com/showthread.php?t=2379618
I've managed to make my way to the platform tools folder in a command line, but running the reboot bootloader command there does nothing. It simply says device not found. I don't think my computer is even seeing the n7 properly so it can't reboot it. I don't think its defective, but I don't know where to begin to fix this using the old fashioned way either....
Click to expand...
Click to collapse
To get into bootloader mode, you hold down POWER+VOLDOWN - not all three buttons. Make sure you turn off your device first (hold down power until it shuts off), then hold down those two buttons.
If it gets to the nexus logo, that means your bootloader should be OK, which means you can probably recover.
The 'adb reboot bootloader' command will not work until the device is booted up, your turned on developer mode and USB debugging, and you allowed your computer to connect.
Assuming you can get into bootloader, look to see if you did successfully unlock it or not. If you didn't, try the 'fastboot oem unlock' command.
If you continue to be unable to boot normally, you will likely need to flash the system image. There is one floating around here (system.img). You can do this in the bootloader as well (fastboot flash system system.img).
hadisious said:
I second all that's been said here. While toolkits can seem attractive, it's really quite simple, and much safer to do it manually once your take an hour to learn your way around the Android-SDK (way easier than it sounds, I promise).
Click to expand...
Click to collapse
I understand that and have absolutely learned my lesson. What's confusing me at the moment is installing the drivers listed in the link I posted. All that's there is a zip file, no exe or anything which is what I'm used to for installers. I was able to reboot my nexus 7 into bootloader before with the toolkit, so I know I had the drivers installed properly at some point. The toolkit installed a universal ADB set which I'm thinking should work. I don't know what to do to get the device into bootloader to follow the instructions.
phonic said:
To get into bootloader mode, you hold down POWER+VOLDOWN - not all three buttons. Make sure you turn off your device first (hold down power until it shuts off), then hold down those two buttons.
If it gets to the nexus logo, that means your bootloader should be OK, which means you can probably recover.
The 'adb reboot bootloader' command will not work until the device is booted up, your turned on developer mode and USB debugging, and you allowed your computer to connect.
Assuming you can get into bootloader, look to see if you did successfully unlock it or not. If you didn't, try the 'fastboot oem unlock' command.
If you continue to be unable to boot normally, you will likely need to flash the system image. There is one floating around here (system.img). You can do this in the bootloader as well (fastboot flash system system.img).
Click to expand...
Click to collapse
So I'm able to get into the bootloader, but its not responding to the command line entries. My computer brings a popup anytime the nexus tries to do a regular boot, where it just sits at the logo. The popup explains that the device is unrecognized. I've uninstalled any devices that resemble the nexus in device manager, and have tried repeatedly to update the driver manually by pointing it to the usb driver folder within the sdk. Doing that simply says windows is unable to locate the correct driver. So I think my device is where it needs to be, I just can't connect to it from the command line at the moment.
First of all, what made you try the toolkit(effective as it is) on the new Nexus...? Couldn't you just sit down for a day or two enjoying stock experience(abominative as it is)...?
alicarbovader said:
First of all, what made you try the toolkit(effective as it is) on the new Nexus...? Couldn't you just sit down for a day or two enjoying stock experience(abominative as it is)...?
Click to expand...
Click to collapse
Unlocking the bootloader will always result in your device getting wiped.
So it makes sense that you do this first, this way you don't need to setup your device twice.
It also has nothing to do with stock vs custom. I have an unlocked bootloader, custom recovery and am rooted. But my device is still completely stock as far as the OS goes. The only thing I might change in the future is a custom kernel, as I am usually fine with things 'stock' from a user perspective on Nexus.
phonic said:
Unlocking the bootloader will always result in your device getting wiped.
So it makes sense that you do this first, this way you don't need to setup your device twice.
It also has nothing to do with stock vs custom. I have an unlocked bootloader, custom recovery and am rooted. But my device is still completely stock as far as the OS goes. The only thing I might change in the future is a custom kernel, as I am usually fine with things 'stock' from a user perspective on Nexus.
Click to expand...
Click to collapse
Honestly I had completely forgot that the initial unlocking does the factory reset. I got caught up in booting up the device and installing a few apps to try it out, to the point that I completely blanked on the reset haha.
I tried a bunch of different roms and verions on my gnexus and old N7, jumping between CM and PA mostly, and I got used to just having a backup ready and not worrying about a data wipe. I've mostly stuck with PA because the pie controls are fantastic on both devices and I've come to get used to the added screen space. I'm perfectly fine with the stock experience outside of pie controls, but I do love customizing my device and the custom roms allow for so much freedom in that regard.
destructobob said:
I understand that and have absolutely learned my lesson. What's confusing me at the moment is installing the drivers listed in the link I posted. All that's there is a zip file, no exe or anything which is what I'm used to for installers. I was able to reboot my nexus 7 into bootloader before with the toolkit, so I know I had the drivers installed properly at some point. The toolkit installed a universal ADB set which I'm thinking should work. I don't know what to do to get the device into bootloader to follow the instructions.
Click to expand...
Click to collapse
Okay... so its a zip file.... go to device manager and it should show you some android driver or nexus 7 or something.... right-click on that and choose update drivers... choose manual method and select the folder hat you unzipped...
then use fastboot to flash factory image...
Q: is factory image for nexus 4 2013 available
??
shengovind said:
Okay... so its a zip file.... go to device manager and it should show you some android driver or nexus 7 or something.... right-click on that and choose update drivers... choose manual method and select the folder hat you unzipped...
then use fastboot to flash factory image...
Q: is factory image for nexus 4 2013 available
??
Click to expand...
Click to collapse
I actually got it successfully up and running, unlocked and rooted and everything. The screen and dual speakers alone justify the price for sure, and the speed difference is noticeable. Riptide 2 seems to run alot smoother on this than my old N7. I'm also aware that in general a clean install runs better than something that's been used for a while, so perhaps that's part of my percieved performance gains. In any case I'm more than happy with my purchase, and am looking forward to getting my chromecast tomorrow!
destructobob said:
I actually got it successfully up and running, unlocked and rooted and everything. The screen and dual speakers alone justify the price for sure, and the speed difference is noticeable. Riptide 2 seems to run alot smoother on this than my old N7. I'm also aware that in general a clean install runs better than something that's been used for a while, so perhaps that's part of my percieved performance gains. In any case I'm more than happy with my purchase, and am looking forward to getting my chromecast tomorrow!
Click to expand...
Click to collapse
:good::good::good:
phonic said:
Unlocking the bootloader will always result in your device getting wiped.
So it makes sense that you do this first, this way you don't need to setup your device twice.
It also has nothing to do with stock vs custom. I have an unlocked bootloader, custom recovery and am rooted. But my device is still completely stock as far as the OS goes. The only thing I might change in the future is a custom kernel, as I am usually fine with things 'stock' from a user perspective on Nexus.
Click to expand...
Click to collapse
Yes but you should've waited for a suitable toolkit.
alicarbovader said:
Yes but you should've waited for a suitable toolkit.
Click to expand...
Click to collapse
Why would I wait for a toolkit?
This is a Nexus device. You don't need a toolkit. All you need is two brain cells and a willingness to learn. You can unlock, flash custom recovery and root in a matter of minutes with nothing other than the Android SDK. Toolkits cause more problems than they solve.
phonic said:
Why would I wait for a toolkit?
This is a Nexus device. You don't need a toolkit. All you need is two brain cells and a willingness to learn. You can unlock, flash custom recovery and root in a matter of minutes with nothing other than the Android SDK. Toolkits cause more problems than they solve.
Click to expand...
Click to collapse
ok, not a toolkit.. I give you that, but was the stock experience too intimidating...?
personally, i'd nuked htc sense when i got thoroughly bored with its great buttery ui. i like the aosp experience, rooted or not.
and i didn't know that we don:t need toolkits fpr nexus devices, cuz i've never happened to own one.

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