The loop response can be measured after simple changing to the board. First, cut net tie (NT2) and install a 10-Ω 0603 resistor on the bottom of board. The change is show as below. An AC signal (10-mV, peak-to-peak amplitude recommended) can be injected into the control loop across the added 10-Ω resistor.

Figure 3-2 Bode Plot Measurement Board Modification