When you power on the MDS100-BW, does the LCD backlight comes on and does it show any start up message and report the ID? If so then the LCD display is still good and the CPU on the MDS100-BW appear to be working and the problem may only be limited to the RS485.
Since you have the Nano-10 I assume you have the U-485 adapter? If so, you can try to use TLServer to communicate with both the Nano-10 and the MDS100-BW to see if you are to able to communicate with both devices via their RS485 port. To communicate with the MDS100-BW you need to know its ID (default is F0 unless you have changed it) and then send the correctly formatted command string with correct FCS. If the device send a correct response that means the RS485 chip on the MDS100-BW is good.