Like the OP, you need to do the following in that order
a. Clear up the codes, pray that the kick goes away.
b. find a very good mechanic and have your valve body checked; either the solenoid is bust or most probably the spring and release mechanism is bust.
Those springs do get tired after a while and need be changed for smoother shift.
Now, lastly I need to tell you, that once the oil is changed, NEVER EVER discard the old gear oil.
The oil must be sieved through very fine cloth and checked for residue.
This gives you a fine marker on the internal health of the gears.
Lastly, NEVER EVER use any oil other than manufacturer recommended ones. ( it's there for a reason )
Should you use one, it renders the warranty void.
Best of luck.