"no command" after OTA update of a Wiko Rainbow 4G
It turned out that the drivers which were installed on my Windows machine were not good enough for flashing. They were OK for normal connection when the phone was working.

I found the correct drivers on the GSM USB DRIVER site. I installed the VCOM version by going into Device Manager, clicking on the computer (upper-most entry) and selecting Action -&gt; Add legacy software. 

The installation failed. So that it goes though the PC needs to be restarted in a mode which allows for non-signed drivers. This is explained in a good video, the steps are to reboot your PC by shift clicking the reboot entry, then Troubleshoot, Advanced options, Startup settings, Disable signed drivers enforcement. After the automatic reboot the installation above will succeed, and then the flashing does so as well.

All credit goes to Android MTK for the tutorials and GSM USB DRIVER for the drivers.