I have a minivator 950 that has stopped working?

i moved he 950 from my mother in laws house after she passed away and installed it into my dads house. where it worked for about a week und then just died.
on further examination I found it needed new brushes to run up the track so it could re charge the battery.
I fitted those and after 2 days popped back and it seemed to be charged but now it will not run.
It has a - in the display but cganges to 8 when I press up, or 9 when I press down....it then changes to a C on the display. my dad is 90 and needs this lift but no-one will come out to it because I installed it.
I just need some one to tell me how to fix it if they don't want to do it but they wont even tell me over the phone, let alone come out to look at it and then tell me how to fix it.
My dad cannot afford to scrap it and spend another £ 3000 on a new one.
Minivator-manufacturer...wont touch it
EMS repair/servicers...wont touch it.