Galaxy S8 Plus stuck in boot loop after using PrinceComsy Odin

Hello and welcome to another #GalaxyS8 troubleshooting article. This one answers a question posted by one of our readers after his S8 Plus stuck in an endless boot loop after an apparently failed modification procedure.

Today’s problem: Galaxy S8 Plus stuck in boot loop after using PrinceComsy Odin

Hello. I have an att samsung galaxy s8 plus g955u. I was in download mode and attempting to do something in Odin Prince Comsy that ended with a FailAuth so I tried to reboot download mode by pressing bixby & vol-up & power but instead it gave me an error msg that said theres been an error please use Smart Switch pc program for recovery, or something along those lines. The smart switch program was not reading my phone so I attempted a soft reset and now my phone wont turn off and instead keeps showing a blue screen that shows the android man with the moving circle arrows in his belly and says “Installing system update” under him. It only shows this blue screen for a second before going to the next screen which looks like as if the system update were installing but that screen only shows for a second too, then the screen goes black for roughly 3 seconds then repeats the 3 screens over and over and has been doing so for hours.

I will say I feel when I first attempted using the odin prince comsy in download mode that my phone might have been pretty low on battery. I feel ive tried every combination of buttons but the 3 screens keep repeating. The phone will let me perform a soft reset but when I hold vol-down and power I feel the phone vibrate for a sec, screen stays black for 3 secs and then shows the opening black and white screen that says Samsung Galaxy S8+ powered by Android and its followed by the blue Installing System Update screen which starts the repeating 3 screens from endlessly repeating. Right after I soft reset, the first time the blue installing system update screen and the next screen that looks like its loading the update show up they are bright like the brightness is turned all the way up but after that first time the just keep repeating but with a really dim screen. I’ve tried leaving it plugged into the charger but no dice, and it doesnt appear to be taking any charge.

Also no lights flash at all from anywhere on the phone, only thing that happens is the screen repeating unless i do the soft reset and i explains what happens then. Again ive tried pressing every combination (i think) of buttons before and after performing the soft reset, ive tried holding the buttons past when the phone vibrates, past when it says Samsung Galaxy S8+ powered by Android and even past that. I’ve tried releasing them early and also right when the screen shows and also changing the combination of buttons before, during and after the soft reset vibration and all following screens. I feel like this is a bootloop (although ive never had one in all my years of ht tinkering and modding my phones in way of rooting, installing recoveries and changing roms) but what’s happening with my phone doesnt match what anyone complains about when they are having a “bootloop issue”. I also cant find ANYTHING online describing what my phone is doing. Im sure its a long shot but…..any ideas??

Sorry for the super long, serious mispelled msg but im dying trying to figure this out. PLEASE any and all information will be MUCH appreciated!!!! Please and thank you in advance for any assistance you might be able to provide!!…Oh also I had the most recent OTA update that was available installed but i’m unsure of what version of Android that was. — Lazerus

How to fix S8 that’s stuck in boot loop and won’t load load Android

Samsung released an update for its flagship devices, the S8, S8 Plus, and Note 8, last January (2018) that brought with it a new bootloader as well as some defense against Spectre and Meltdown security loopholes. The new bootloader was designed to prevent downgrading a device’s firmware version to an older one. It also appeared to be a direct attempt to negate the usefulness of the modified Odin by PrinceComsy, which has increasingly become a popular modding tool for many these days. As you may probably known, the main reason why PrinceComsy is an excellent choice for modders is its ability to allow using another firmware from another region. So, if you have an American S8 that runs on American firmware, you can now actually use a Canadian firmware version (as long as you have a compatible SoC of course) with the help of PrinceComsy by Odin. With Samsung’s January update, a new bootloader will no longer allow changes to the firmware. We don’t know what you were trying to do exactly but if your S8 Plus was updated with a January update before you used PrinceComby, this may be the reason why it’s currently bricked.

According to this XDA article, Odin PrinceComsy should still be working properly at this time even though Samsung has attempted to patch it along with other known vulnerabilities for its January 2018 security update. It does not give details how to fix a bricked device though.

Though we haven’t tested it in our laboratory, we suggest that you try reflash the bootloader and firmware back to their official build whatever they may be and see what happens. Any experienced modder takes note of their device’s bootloader and firmware versions before modifying them so we would like to assume you did that too. If you didn’t do that, which is really foolish, then try to get one identical S8 Plus and check their bootloader and firmware versions. Once you have the information, download the necessary files and reflash the bootloader first, then the firmware second.