hi everyone, I'm new here, pls. be tolerant if not perfectly adapted,

since some releases I experience that Lenovo P70 touchpad, pointer stick, and external usb mouse:
DO work with 'live stick', but
DO NOT work once using 'persistence' or 'encrypted persistence',
I searched and found plenty of similar reports about installed versions having trouble after
upgrade, but couldn't test the hints there ( modprobe -r psmouse, sudo apt-get install xserver-xorg-input-synaptics )
because I couldn't manage to open a terminal - even any program - without working pointer.
Anybody a hint to solve without building individual images.
AFAIK the input devices are some flavour of synaptics.
TIA for any help.