As far as I know, there is no manual override. The seat has to be removed
to access the motor and drive mechanism.
--
Ray O
(correct punctuation to reply)
You'll need to get the switch assembly, if it's bad, from Lexus. But
the motor, if bad, you may be able to buy from the local Toyota
dealer. The RX is a modified Toyota Camry, similar to the Highlander.