820-01598 no keyboard or trackpad

[tcampbell34]

I got a 820-01598 that was liquid damaged around the trackpad connector and did not turn on. Trackpad connector was burned on PPVIN_S4_TPAD_FUSE. I cleaned the area and replaced the trackpad connector with a new one. All diode mode readings on the trackpad connector seemed to match a good board now, so I plugged the board in using another known good trackpad and it boots to the OS, but keyboard and trackpad do not work. I rechecked all diode mode values on the trackpad and keyboard connector and made sure there were no broken traces there. With the trackpad connected, I was not getting any voltage on TPAD_SPI_EN, which comes from the T2 chip. I removed U6855 and found I have OL on pin 1, which is not normal. Seems the trace between the T2 chip and pin 1 of U6855 is broken. I cannot run a wire without removing the T2 chip, which I do not want to do. Wondering if I can connect Pin 1 of U6855 to TPAD_3V3_SPI_INT_L, or some similar signal to make it work? Any ideas?

 

[2informaticos]

KB/TP work in USB mode, before loading macOS (boot menu)?

Keep out U6855 and bypass R6854 pads.
Let see if this tricks the T2.

 

[tcampbell34]

No the trackpad does not work even in boot menu.

I did what you said, but still same thing. No keyboard or trackpad

 

[2informaticos]

TP SPI data lines don't go directly to T2.
But who knows, level shifters may got damaged and affected T2 too.

Maintain the bypass and try changing U6860.

 

[tcampbell34]

I tried another trackpad from an A1708 because I was not sure if the trackpad I was testing with was actually good or not. With the A1708 trackpad, it works in the boot menu, but then does not work in the OS or recovery mode.

 

[2informaticos]

macOS accesses TP through SPI bus and you have missing the required enable signal.
Did you test maintaining R6854 bypass?