I have gotten the warranty part. Still encounter little problem on the communication.
The new RF module were responding fine to AT command until it respond like this. Do you know what happen to it? I can't make it to respond OK instead. Does this indicate that I overwrite the firmware? Restart the PC, disconnect and reconnect the RF module shows the same result.
Both RF module respond incompletely, Module #1 respond with additional weird character along while for Module #2 some characters are missing. If you look at the picture, I tried the all Capital letters on keyboard following by small letter and then lastly the single digit integers.
Module #1
Module #2
FYI, I have used the same setting for both modules.