A friend had two H controllers. One was severely damaged: all buttons except the left and right sticks, L3, and R3 were nonfunctional (because years ago it was soaked in cola…). The other had L1, L2, and D-pad up and left failing, while the rest worked normally. Opening them up:
The back cover showed it was an H controller, with the board marked 760020 in white at the top left. This is the second version of the H controller. The conductive film under the button pads was marked 03-0241. On Taobao I found similar films for about 2 RMB each. Observing the connection between the board and the conductive film, I confirmed that the film connector and socket are integrated, with the socket pins soldered directly to the PCB. Comparing with my A controller, its conductive film is pressed directly onto the PCB. Taobao did not sell the original socket type film, but luckily one seller offered a similar 19-pin pluggable socket.
Looking at the PCB traces and referencing information that PS2 DS2 controllers support pressure sensitivity, the conductive film carbon contacts change resistance depending on button pressure, which the BU6370AK main chip converts into digital signals for the console. Examining the film traces, I saw that except for Select, Start, and Analog buttons, all carbon contacts shared one common line, corresponding to pin 9 from the left. Using a multimeter with one probe on pin 9 and the other on each button pin, pressing a button showed resistance changes from 0 to several kΩ (tested on the partially working controller). On the faulty buttons, it was open circuit. Comparing traces, L1, L2, D-pad up, and left corresponded to the leftmost pins, while D-pad down (which worked) was the next pin after left. So I concluded those four buttons had broken traces on the film. The other controller was worse: all buttons failed, only the analog sticks worked. Despite the cola damage, the main chip seemed fine. So I ordered replacement films and sockets from Taobao.