I just changed the hotend somedays ago.After testing the flowrate,my exturder can’t turning anymore.
I have checked the cable and voltage,but everything looks working well.Also i bought a new cable and new motor,nothing goes well.The problem still.
Now I’m asking creality for a new motherboard,but it needs some days to get it.
i have no any other idea about how to try on.
Can anybody helps me
(I’m not navtive speaker,hopes guys can understand my sentences)
Hello @Yitangs …! 
Welcome to the Creality Forum…! 
The problem started after you changed the hotend…?
Are you seeing any error messages or any strange noises…?
Look underneath for loose connections and all that…?
Thanks for replying!
Yes,after i changed a new “heater block?” and flowingrate test,it suddenly not work.
There is no error message on the screen.When doing “axis move” on screen,the motor can be locked.Then using the “moving extruder”,the motor will shake once,just like made a veryfast retract,but didn’t turning any.I can easily move the gear by hand after this happened.
I have checked both side of the cable.Nothing loose and have tried plug all the cable on and off.But didn’t help.
Even the new cable and new motor act as the same.
Trying to get an idea of the problem here so someone who is really familiar with those extruders can suggest a fix.
What was wrong with the original hotend or heater block that you replaced…?
It’s a 2ndhand printer actually.Last owner replaced the hotend by ender3 s1 pro hotend.It can’t work properly so i get an original one to replace it.
Maybe i can only wait for the new mainboard to fix it.Im guessing the driver was broken. 
Finally i fixed the problem by changing the mainboard.
Maybe the driver was broken i think.But all the voltage were tested correct.
Confused.
