I am curious that after you replaced the actuator did you perform a calibration?

A flashing lid lock light in short can mean
1. faulty lid lock (you've replaced and ruled that out)
2. motor can not be powered, due to:
a. Basket speed fault
b. Shifter fault (you've replaced actuator and ruled that out)
c. Motor fault
d. Motor unable to reach target RPM
You having ruled out 2 issues pointing to a problem with the motor starting or reaching desired RPM. In my experience a major reason for this is a faulty motor run capacitor. These tend to loose their capacitance and will either not start the motor or cause it to not run properly.
If you have a digital multi meter, set it to capacitance test mode and check your capacitor to see if you get between 47.5 to 52.5 uF (microfarads), anything outside this will cause problems running the motor.

If your capacitor is bad here is the part you need.
Whirlpool W10804664 Capacitor - AppliancePartsPros.com