Chips to remove:

U4 - TCA6416RTWR - (the only large ic on the power board)

This chip handles IO Expansion for all the buttons.

Test points to tap:

// ON THE POWER BOARD
13 - 5v from the USB
19 - LB
20 - RB
21 - A
22 - X
23 - Y
28 - LED through Q3
39 - Share

// ON THE MCU BOARD
63 - LStick Y
65 - RStick Y
67 - RTrigger
68 - LTrigger
112 - RStick X
DT - Left Sick X

Right Stick Points

Left Stick Points - Direct Tap

Power Board

Test points to pull high

TP113 Enables TRG+ for the left and right trigger via TLV707

TP36 Enables the 1.8v Rail needed for the analog sticks va MP1476L