good news
:good:i just found the solution to this "failed to boot 3"
ONLY FOR SKT & KT VERSIONS
for this korean skt phones, by following the guide lines you will end with the "failed to boot 3" screen's only
the tricky part comes here: (for korean skt atrix mb860 users only)
after downloading RSD Lite and int-fix-try1.sbf
you have to download one more sbf file which is austrilan roman (size=617.462mb)
http://www.startpda.kr/zbxe/index.php?mid=pds_rom&category=1217833&document_srl=2494955
transilate it so you can understand it.
now run the RSD Lite then connect the phone with (100% charging) press the power+vol up key,
there you see the failed to boot 3 & starting RSD. then you see the RSD has connected...
now press the ". . ." & then choose the big sbf file you have just downloded now it will take some
time for com completing 100%. and now your phone will reboots with austrilan rom.
then you can flash the "int-fix-try1.sbf' finally you can follow this thred's guide lines.
hope this will help all those korean users to unlock there bootloader sucessfully.:highfive: