Is there a way you can confirm the baud rate the device is seeing? One way to check could be to send some command that does something verifiable on the module like flashing some led or something. This way you can confirm that the device is indeed operating at the correct baud rate. Then comes the return information check. Are you able to see simple things like maybe a AT OK coming from the module? If not, is it possible you might be seeing inverted data?

These are some thoughts that come to mind