It is a hardware feature of the TSDZ2 controller.
If the brake sensors are active at power on, communication between the controller and the display is inhibited, nothing works.
With the stock displays (VLCD5, VLCD6, XH18) no message is displayed, it is not provided for in the displays and, since there is no communication, it is not possible to send it from the controller.
You can only notice it from the zero SOC bars and the fact that there is no assistance.
Some more recent stock displays, of Bafang origin, show err30, communication problem. But it is provided for in the display firmware.
The version for 860C displays being programmable, the message "Error brakes or comms" is provided.
With LCD3 no message is provided, the system stops at the boot screen.
In theory a message could be added, but I have no plans to continue development for this display.
Also, the memory is full, there is no space available for any changes.