A friend corrupted the firmware so now it doesn't do anything.
I found the Mblock IDE https://ide.mblock.cc which runs in my browser, and connected the Mbot via USB.
Then I clicked on the MBOT and up came a small window that said I needed to have Mlink 2 running, then gave me a link to get it, so I have downloaded it.
It's installed but the IDE says I can't connect until it is turned on.
from here, way down towards the bottom:
https://education.makeblock.com/help/obtain-and-install-mblock-5/
there is this command:
(2) Enter the following command to start the program:
sudo mblock-mlink start
Note: Do not close Terminal After opening the program. Otherwise, the device communication is disconnected.
Enter the following command to stop the program:
sudo mblock-mlink stop
OK, this connects. Now how to restore initial program.
https://www.vernier.com/til/4153
at the bottom of this page there is a link to a troubleshooting page.
I think the batteries may be low. Batteries were very low. Try reflashing again.
New batteries and updated with Factory firmware and not on-line firmware, and it is sorted.
end of blog. 18/10/2023