Change boot splash image from inside

jezek

Just a crazy idea, that brought up a question. Is it theoretically possible to change the boot splash screen image using only the phone itself?

RESTRICTIONS
Not using some external commands via adb os ssh. Just using terminal and some skillfully crafted program.

Thank you.

zubozrout

@jezek You should be able to write the correct partition image (could be called e.g. "logo.img") using dd command right on the device but in order to do that you would have to have that image prepared already.

This is however very much device specific: https://forum.xda-developers.com/android/software-hacking/guide-how-to-create-custom-boot-logo-t3470473 so you would ideally have to check the correct instructions for you phone. And I expect such thing (if the XDA instructions do not recommend a Windows executable) would be doable on a phone as well but it would certainly not be the most comfortable way to deal with it.

jezek

@zubozrout parada... ehm... great

So, let's say, we have a custom bootlogo for my device, named splash.img. Any hints, where should I start to look, if I want to use the dd command to rewrite the splash screen image? And is there any possibility, that I could irreparably brick my phone, if something goes wrong?

zubozrout

@jezek Well, you would need to find the partition table of you phone to find the correct partition to flash the image to.

Not sure what would happen if the boot logo image was incorrect, it would work nonetheless (with a black screen) or perhaps it would brick the phone and you would have to reflash the correct image using fastboot then ... something like fastboot flash logo splash.img (the command may not work at all or could be different depending on the device).

And if you flash it to a wrong partition there is a great chance of bricking the phone.

jezek

@zubozrout thank you for your answers.

flohack

@jezek and beware, of course you can brick things. E.g. There is a notorious logo brick with the OPO, if you flash the wrong image data it will be bricked. Thats a part of your phone which was never meant to be modified

Also it can be that the bootloader prevents flashing this partition when an OS is running. You need to find out.

jezek

@Flohack thanks, for warnings.

What I wanted to know, if somebody knows about some write protections to bootloader. So currently we are not sure if the bootloader protects itself from changing while running, right?

flohack

Please dont touch the bootloader, this will brick your device for sure - the splash screen is in a separate partition for all devices I know, so that should never need to touch the bootloader itself.