Can computer imposed inputs be overridden on the Boeing 737-MAX?
The new 737 MAX has a more advanced pitch control system called maneuvering characteristics augmentation system (MCAS), which automatically adjusts the stabilator trim in case of high thrust and high angle of attack (AOA). This makes it very hard to overcome the down force with elevator input alone (pulling up).

In case of a wrong trim adjustment (e.g. due to an erroneous AOA sensor), the pilots have to adjust the trim manually and maybe even turn off the stab trim via the cutout switches in the center pedestal (shown below). This was apparently not conveyed properly in the MAX differences training and the FAA has since issued an Emergency Airworthiness Directive.

737 NG:

(image source: flaps2approach.com)

737 MAX:

(image source: feitoffake.wordpress.com)

So compared to an Airbus, the Boeing pilots can still have all manual control, but they have to use manual pitch trim.