Thanks for testing — this result is really helpful!
Since i2cdetect -y 1 detects an I2C address when only the Robot HAT is connected, both the Pi and the HAT are fine. The problem is with the modules or cables connected afterwards — most likely one cable is in the wrong port, plugged in backwards, or not fully seated.
Please recheck and reseat the wiring of each module following the assembly video:
I’d suggest connecting the modules one at a time: after each one, run its corresponding test example in ~/pidog/test, and only move on once it works (please power off before changing any wiring). If a module fails its test, send us the module name, the full error message, and clear photos of the cable at both ends, and we’ll help you check.