MacBook Pro Early 2015 - Trackpad (but not keyboard) problem diagnosis

Hi,

I need advice diagnosing my problem:

• Early 2015 Macbook Pro
• Keyboard and Trackpad became unresponsive.
• Apple suggested water damage ($750 repair).

Steps tried so far:

• All the software related fixes (PRAM, SMC reset, recovery mode, using ubuntu live booted from USB). (external connected USB keyboard/trackpad work however)
• Cleaned corrosion on the trackpad control board (using 99% IPA)
• Took the trackpad cable out, cleaned (using 99% IPA) and put back in
• The keyboard started working but still not the trackpad.
• Then replaced the trackpad cable with one from iFixit, but the same issue remains - trackpad doesn’t work, keyboard works.

What could be causing just the trackpad to not work? And is it likely that replacing the trackpad will solve this issue or could the problem be elsewhere?

Thanks

D