The mini has a really poor quality Touch FPC connector and it’s quite normal for a few pins to lift when disconnecting the flex. That said, an FPC replacement is usually all that is needed. Continuity testing the pins is a good step but I also like to do a “push test”, meaning that I push on the leg (that is soldered to the pad) very lightly with a fine tip probe to see if there is any movement. If there is, you may have a weak connection and this could be causing issues.
I would also check the surrounding components as one may have been fully or partially dislodged. Finally, I would probe the pins in diode mode and compare to a known-good connector (the mini 3 digitizer FPC has a different configuration to than the mini 2 so you can’t use that).
Beyond that, it could be a Touch IC or Touch Power issue.