This one is a tricky one but you can still do it.
You have the arch logs in a unreadable binary format so you must first convert it into ANSI format.
first dump the file using
Code:
svrmgr> alter system dump logfile < logfile_name > < options >;
options has stuff like blockno, etc

To check if all of the dump file was written correctly at the end you must have 'END OF REDO DUMP'

if a particular scn can be provided then maybe you can attempt to recover the db before that 'troublesome 'scn.