820-4925 Shift key stuck

[No-Clean]

Clean board, with disconnected keyboard the mac starts up in safe mode and shift key is stuck sometimes enter key doesnt work and or when you press a normal key such as "j" it prints a weird character instead of a "j" same happens with some of the other keys on that same row.

I also tried new trackpad and trackpad cable, same thing.

Also checked and reballed U4820/30 and checked all the pull-up resistors R4850-62 all are good.

Connector looks clean and inside of it is also clean, going nuts here, first time with this issue.

 

[2informaticos]

Post voltage for pins 1 & 8 of U4850.
I had similar case, where I found corrosion underneath J4813; between pins 3 & 4.

 

[No-Clean]

Voltage for pins 1 & 8 of U4850 0v even with keyboard connected and SSD

I will resolder J4813 now and test

 

[2informaticos]

In such case, is not Left Shift key issue.
Check if other output of U4850 stays high.

Can you access boot menu?

 

[No-Clean]

I replaced U4820/30 and U4850 also resoldered J4813 MBP is working fine now.

Thanks!