the contents are put into temp folders and nexon's launcher is unreliable when resuming (which is why third party launchers exist) so a locked client.exe is enough for nexon to fail and any file not updated correctly wither it be mabi files like client.exe, packages, nexon guard or hackshield itself with an old file will cause hackshield errors.
If a patch fails because of a locked client, the patcher
DOES NOT perform the update.
The patcher also
makes backup of your old files BEFORE REPLACING THEM. If for any reason the patch fails,
THE BACK UPS ARE USED.
Even if you disconnect while patching,
the client does not RESUME file part, it
ABORTS. It will begin downloading from
THE FAILED PART, meaning
THE PATCH NOT CORRUPT.
If HShield/NXGuard is not up-to-date, it will
UPDATE.
Again,
PACKAGE FILES do not cause
HACKSHIELD ERRORS.
If your patch fails for any reason (including a locked client),
THE PATCHER KNOWS. It will
NOT CHANGE TO THE NEW VERSION. (WTF?)
Hell. He even states that
he does not use abyss. Meaning the only way for his client to have been locked
would be if he was RUNNING MABINOGI while trying to patch. Even so, that's only possible if he
MODDED HIS LAUNCHER, which is doubtful because there'd be 0 reasons to.