Just finished putting together my new FT-5 R2, and I have been impressed so far. I finished assembling the kit about a week ago, and after a few minor issues that were likely due to the stepper drivers being tuned too low for the Y axis, I managed to output some great prints.
However, a few days ago, as I was starting a print with PETG, and I noticed that the extruder was not feeding any filament into the hotend. I then double-checked the voltage on the stepper driver, and it was sitting at 0.8V (seems OK to me). Through further troubleshooting, I found that any motor that was plugged into the "E0" plug would not function (the extruder motor would function fine on any other plug, and the stepper driver would also function on any other socket). Thinking that there could have been a short on the MKS board near the E0 plug, I ordered a replacement. The replacement came, I flashed the stock firmware on it, installed it, transferred over the working stepper drivers, and again tried to extrude filament during a print (with the extruder disassembled to the bare motor to make sure that the lack of extrusion was not due to excess friction) but the motor did not move. All driver motor voltages are where they probably should be (X,Z, and Extruder between 0.8-0.9V, and the Y at about 1.3V).
Also, due to the stepper motors working on other plugs (non E0 plugs), I think that the error could be the somewhere on the MKS board (that is why this post is in "Controllers" and not under "Extruders").
Any help you all could offer to get the printer working again would be greatly appreciated!