Eric, thank you! I had exactly the same problem. I followed your steps and I can connect again via the wireless USB now, exactly how you described. Still wondering though why suddenly it wouldn’t work anymore via the wireless USB, only with the cable connected. It was working fine when I used it the first time. One month later suddenly it wouldn’t connect anymore, on the same computer, with the same settings. Is it necessary to upgrade the firmware regularly?
Frustrated by the 2.4 GHz module
chuckmcknight
#23
At a minimum, you should upgrade the firmware every time you upgrade mBlock. Otherwise, you can use the upgrade firmware option to get the robot back to a known good state. 
eric03
#24
Cym, Chuck’s suggestions are excellent. From your post, it wasn’t clear if you are having trouble making the serial connection to the robot from your computer or a later stage. That requires the correct USB serial driver on your computer, and often Macs (like I have) have trouble making that connection. Assuming you can connect, though (and you can tell if there is a check mark next to the serial connection menu choice, the you need to make sure the arduino in the robot has the correct compiled code. The code might have been corrupted (or you are using a different robot?), or a new version of makeblock might have a different program to run on the robot’s Arduino. In either case, once your serial connection is working (the menu item is checked), then you can upload the compiled program to the robot. That is what the “Upgrade Firmware” menu item does. The little window that appears will tell you if the upload was successful and when it is done. If that works, then go back to the Serial Port menu item and unclick the serial port option. Once it is unclicked, you can choose the 2.4Hz wireless option (as you have done in the past) and you should be all set. Chuck summarized all this in two sentences, but I thought perhaps a more complete explanation might help.
ChrisNZ
#25
We have been using 15 Mbots for a year. We upgraded Mblock software in February. Last week all was well. This week none of the 15 will connect via the wireless dongle. Have upgraded the firmware as per the instructions above but still nothing. Sometimes the green dot appears to on the Robotic section but when you run the programme it does not respond on the mBot.
Is there anything else we can try besides upgrade firmware. The only thing that may have affected it was that we downloaded a programme to the mbot using the usb cables. After we unplugged and went back to wireless, it would not connect.
Seems strange for them all to go wrong at the same time.
tech_support
#26
Hi Chris NZ,
You may try pair the 2.4G USB dongle and 2.4G Wireless serial module for each mBot again. Refer to this document.21. Some sets of my 2.4G mBot have lost the pairing relations which lead to mixed together, how can I pair each 2.4G module with its 2.4G adapter again.docx.zip (10.4 KB)
Besides, the latest mBlock version is 3.4.6 now, I’d suggest that you update the software to the latest one. Then upgrade firmware for the mBot again with latest mBlock.
Once still the problem, is it possible for you to take a video to show all your operations (upgrade firmware for mBot, disconnect USB and connect 2.4G serial, test a mBlock online program)
vrbik
#28
I had no problems with working via wifi serial. It was hard to write a code in python, so I do not have to use mBlock sw for robot control. If you are interested in windows solution with pywinusb check this https://vrbaj.github.io/mbot/.
Good luck with this awesome robot! I think students are really excited about mbot.
rajut
#29
I bought the 2.4 for my kid and started exploring. I upgraded the firmware with USB cable and then disconnected the USB cable. Connected the wireless device to my windows 7 PC and its connected in mblock. Now how can I run the program.
There are no clear tutorials of how to send the commands via wireless connection. When I clicked on robots it is showing green icon means connection is successful
If I want my mbot to move forward, I used the run forward at speed 100 and clicked on flag icon, but nothing happening.
Bare minimum you should have a tooltip showing the flag and red dot meanings. Please help on how to run the commands on mbot
tech_support
#30
Hi rajut,
Here is an instruction to guide control mBot 2.4G to mBlock and wireless run the program on mBlock to control the mBot.
18.How to connect 2.4G wireless to my mBot.docx.zip (11.8 KB)
Besides, here is a link provide the mBlock program materials for mBot.
And here is a FAQ list for mBot to you for reference.