GRBL starts spitting out error 1 and 2 when I mount CNC shield on Arduino

Greetings people!

I am stuck with GRBL to the point where I am unable to communicate with Arduino. The connection is fine when I initiate a serial connection with Arduino without the CNC shield and I can communicate. However, when I mount the CNC shield, GRBL goes crazy and starts spitting out error codes 1 and 2 (please see screenshots attached). Could anyone help me out? Thanks in advance!!

 

I didn't get to the stage where I could input the gcode. I just uploaded grbl to Arduino Uno and tried to connect it to OpenBuilds Control and the interface just hangs up and I see the error (check 2nd image of the first post). It's driving me nuts:/

 

I am using a genuine Arduino but the shield isn't. I'll try to find a genuine shield in that case.

 

I found the problem. The buffoons who soldered the knockoff CNC shield had done such a poor job that they soldered TX and RX pins together. Therefore, Arduino went crazy every time I mounted the shield. I resoldered and separated the two pins, and now everything works like a charm. Thanks for your suggestion; otherwise, I wouldn't have inspected the shield!