So, yesterday I took a lot of time to figure out what issues I was having because one TSDZ2 wireless board was not working... turns out I was very tired already and exchanged the UART TX and RX wires. I had to use the oscilloscope to discover that the constant "alive" signal sent by the motor controller was very small and near 5 volts, so, the wires were exchanged. But after, the system still not worked, the firmware correctly turned on/off the TSDZ2 motor controller power and the TSDZ2 wireless board was never sending any data to the UART RX line of the TSDZ2 motor controller. Finally I decided to remove the NRF52840 for a new one and the system finally started to work
So, lesson learned: if by mistake I exchange the UART TX and RX wires, possibly the NRF52840 will be damaged only on the UART RX line of the TSDZ2 motor controller and the system will never work.
And new enclosure, with four M2x6 screws, which makes more easy to open for repair if needed. The board button is still clickable, as the cover was designed to be flexible on the button area.
Now I will add just a small amount of silicone, mainly to seal the unit, cover the LED hole and the cable hole. I will also probably put a small amount on the wires, just to keep them in place and avoid they break with the strong vibrations while I ride my ebike: