Hello Ben, Please control 2 things at first:
1/ control the automatic transmission fluid level and colour (red)
2/ control the inching pedal and valve on the transmission, when you press the inching pedal (left pedal) you press in an axle on the transmission valve. When the pedal is released the axle has to come out completely!
If the colour of the oil is black I think that the clutch plates are burned :(
kind regards
Marcb