Chosen Solution
I recently replaced the trackpad (and mounting brackets) on my MBP, as it had been damaged by a swollen battery. I thought the new trackpad was faulty, but it turns out that it works fine, as long as I am touching the laptop body! I assume this is an issue with electrostatic charge or similar, so that by touching the rest of the laptop I am somehow completing a circuit? When I’m not touching the laptop (so that the only contact is with the trackpad) the cursor behaves erratically, but as soon as I touch the aluminium body it works perfectly. Do I need to somehow ground or earth the component? Any advice greatly appreciated, please!!
Is the flex cable Ok? Are completely you sure you attached the flex cable correctly after mounting the new trackpad?
