Hello,
Basically, the
'factory reset' operation is the same as formatting a new file system in the
cache and
user data partition.
By looking at your log, this devices using latest firmware A.13,
and there was a
failed report when you did a 'factory reset' operation,
probably due to incompatibility of the file system.
If you ignoring the failure above, the device will fail to boot because it cannot mount the user data partition.
To fix this problem, especially on Oppo A3s with firmware A.12 and above,
rewrite the
user data images to user data partition from the extracted OFP of latest firmware.