Binary data gets written as string literal - how to convert it back to bytes?

Assuming type str for your original string, you have the following raw string (literal length 4 escape codes not an actual escape code representing 1 byte):

s = r"b'x\x9c\xabV*HL\xd1\xcd\xccK\xcbW\xb2RPJ\xcb\xcfOJ,R\xaa\x05\x00T\x83\x07b'"

If you remove the leading b' and ', you can use the latin1 encoding to convert to bytes. latin1 is a 1:1 mapping of Unicode code points to byte values, because the first 256 Unicode code points represent the latin1 character set:

>>> s[2:-1].encode('latin1')
b'x\\x9c\\xabV*HL\\xd1\\xcd\\xccK\\xcbW\\xb2RPJ\\xcb\\xcfOJ,R\\xaa\\x05\\x00T\\x83\\x07b'

This is now a byte string, but contains literal escape codes. Now apply the unicode_escape encoding to translate back to a str of the actual code points:

>>> s2 = b.decode('unicode_escape')
>>> s2
'x\x9c«V*HLÑÍÌKËW²RPJËÏOJ,Rª\x05\x00T\x83\x07b'

This is now a Unicode string, with code points, but we still need a byte string. Encode with latin1 again:

>>> b2 = s2.encode('latin1')
>>> b2
b'x\x9c\xabV*HL\xd1\xcd\xccK\xcbW\xb2RPJ\xcb\xcfOJ,R\xaa\x05\x00T\x83\x07b'

In one step:

>>> s = r"b'x\x9c\xabV*HL\xd1\xcd\xccK\xcbW\xb2RPJ\xcb\xcfOJ,R\xaa\x05\x00T\x83\x07b'"
>>> b = s[2:-1].encode('latin1').decode('unicode_escape').encode('latin1')
>>> b
b'x\x9c\xabV*HL\xd1\xcd\xccK\xcbW\xb2RPJ\xcb\xcfOJ,R\xaa\x05\x00T\x83\x07b'

It appears this sample data is a zlib-compressed JSON string:

>>> import zlib,json
>>> json.loads(zlib.decompress(b))
{'pad-info': 'foobar'}