When you upload a program to mBot through the mBlock software, you replace the Default Program (that was shipped with mBot) with your own program. If you would like to reset your mBot back to the Default Program, do the following:
1. Power on mBot and connect it to your computer (PC/Mac) via USB cable.
2. Open the mBlock software and choose "Serial" from the Connect menu.
3. Select the COM (USB) port to which mBot is connected.
4. The mBlock software should now be connected to your mBot. If you are having trouble getting them connected, see TIL 4137: I cannot connect to mBot (PC/Mac/ChromeOS)..
5. Open the Connect menu again and select "Reset Default Program" > "mBot".
6. mBlock will now upload the Default Program. When it is done uploading, mBot will give three beeps.