Indecipherable Data on Serial Monitor
The first hex screengrab (at 4800 baud) looks promising: 

What you are seeing is a 4-byte message. The message is not in ASCII  so it's not human readable. The message is coded in binary (or hexadecimal, if you prefer) and so we need to view and interpret it in that way. Binary typically results in shorter messages than ASCII.



Figure 1. The ASCII table may help in some cases. 'OD', which appears in your screengrabs, is the 'CR' (carriage return) character.


Each line starts with ASCII character 'q' (0h71). It's probably a preamble.
The second character in the responses you have posted is ASCII '$' (0h23) or '#' (0h24).
The third character is fixed as 0h0F.
The fourth character appears to be a checksum. You can confirm this using your computer's calculator in Programmer mode. Select 'byte' data type (to truncate to 8-bits):


0h71 + 0h24 + 0h0F = 0hA4.
0h71 + 0h23 + 0h0F = 0hA3.



You haven't given any information what you did to generate the $ and # symbols so I can't help any further at this time.