After exchanging the T7 ECU for a couple of times, as i was experimenting with the T7Suite for diagnostics and tuning, i decided to pull the cable into the passengers aera to have an easy access to the P-bus. Also this enables to monitor and modify the ECU parametering more closely.
Now i can flash inside the car. After the flashing is successful just take out fuse 17 for a second and put it back in again. Now the new firmware of the ECU is activated.
Luckily we still have the snappies: