I saw a few threads about similar issues but the solutions didn't work for me so I'm starting a new thread. My RAMPS board blew out my Arduino Mega 2560 in my Robo R1 (not the plus version). I purchased an MKS all in one board, and was able to get it to connect to Matter Control briefly but it stopped connecting before it was set up. The next step was to revert back to the Arduino/RAMPS set up. I was able to install the Arduino driver with Windows 7 showing that it was correctly installed (no Windows errors detected). Arduino 1.8.13 doesn't show that it's linked even though I set the USB com port to 5 which is what is shown in Windows 7. Matter Control also doesn't show that it's connected, and keeps hanging while saying that it's connecting. Cura is doing the same thing. It's not a problem with my computer because I have a Monoprice mini delta which connects, and works with Matter Control. Here's what I've done so far: 1. Installed the Arduino software with a device driver. 2. Swapped USB ports & cables. 3. Set the correct port in the printer's settings, and in the print profile. 4. Set the software to use the original Robo profile which came with it, and my custom profiles with various filaments. 5. Tested the computer & software with another printer (Monoprice mini delta) , and confirmed that it's not a hardware issue since that machine works. 6. Tried different baud rates. The only thing that I could think of is that the MKS board, and the Arduino boards are defective even though Windows recognizes. I can't install Robo firmware since it won't connect. What else should I check?