I put it in download mode and start flashing. Odin says fail after sboot and my phone says secure check failed. any solutions?
edit:My bad, i downloaded the s8 oreo
There is a new security feature in OREO for the S8 PLus that has been on the NOte 8 for a while now. IT doens't effect everyone flashing OREO, but it does effect some -
Essentially it is a thing called RMM State - if you are PRENORMAL - you cannot flash anything custom, you will get the error about Official Binaries only - if your RMM State is NORMAL - you can flash custom recovery. (If you go into DOWNLOAD MODE when you are on an OREO ROM, you can see RMM State listed there - it will say either Normal or PreNormal) If you are 'Pre-normal" you will probably also not be able to unlock OEM in Developer settings, in fact it won't even be visible.)
however, if you get the Only Official Binaries error when you try to flash (that means you are PRENORMAL) you can wait 7 days (168 hours) and your phone will revert to NORMAL - and then yoiu can flash TWRP. (you will see OEM unlock in Developer settings again) BUT, if you do flash a custom recovery and or a custom rom, you will need to flash the RMM STATE FIX outlined in this thread in order to stay "Normal".
https://forum.xda-developers.com/showpost.php?p=75360965&postcount=22 If you do flash that Fix - be sure to flash the fix IMMEDIATELY After flashing a custom ROM - or if you only flash twrp, as soon as you have flashed trwp, boot into recovery and flash the fix. if you allow the phone to boot up before y ou flash the fix, it will probably go back to the lock state again and you will have to wait another 7 days.
If you don't want to wait 7 days, you can flash NOUGAT Again in ODIN and you will be ok. OR, you can flash NOUGAT in ODIN, then flash TWRP and follow by flashing "Minotaurus Rom" (Find them on Telegram) and you will have OREO. (But if you do flash Minotaurus, keep your NOUGAT Bootloader) (When you flash Minotaurus, they give you the option to upgrade your bootloader - don't do it - and you will be fine)