pls @autos gurus, is it possible for a car brain box to totally damaged a gearbox? got this 2000 Toyota Camry V6 Automatic last year, after using the car for two weeks bin the owner, it started this black smoke of which i took to rewire(IBADAN) and said i have to change the brain box, i took it back to the dealer and got it fixed, like 4 weeks a go when i visit my family in OSUN, i changed the gear oil, like 7,8 days ago the car doesn't move well at all and it won't move from gear 1 and will jump to gear 4 after high rev up to that red zone....i try to fix the gear as they change the filter from underneath, no improvement, because as they repaired it and bought oando ATF that of 800 naira per litre, the oil got burnt instantly after we test drive the car. thanks to Mayor who advised me to buy another gear because gear repairer wan collect 30k for them to remove the gear completely and repair(how much is gear sef), bought another tokunbo gear 5 pin 60k. after installing, the gear selects only 1 an 4 again but with no high rev,i didn't noticed i though it was okay until i took it to that my rewire(OSUN STATE) to fix all whatsoever wires the mechanic myt have tampered with during the process of installing and he test drive it and he simply concluded the gearbox is the problem and he changed the brain box (20k) and it selects well. the rewire told me that:

1. That the brain box the dealer changed it to is not good and it is because i didn't notice whether the gear selects or not that's why i don't know and it let some stuffs melted together in the old gear box, (is this true).
2. That BRAIN BOX CAN DAMAGE A GEAR. (is this really true).
3. That i have to put 7 litres of ATF Fluid because the gear just installed, i agreed with 5 litres, am i wrong? or not? even though it doesn't guage correctly yet but i can't risk anything

..S/O to Mayor,,i disturb that man no be small .........