The connections on the hotend are all good.
Before trying to heat up, nozzle temp shows ‘err’ under temp. I was able to make it go away and show 0 temporarily after reconnecting the extruder cable, but that is not working now.
Bad extruder cable/connector?
Any other thoughts?
I have the same issue, I do have more than one SV06 and have swapped Extruder cables and have swapped the issue betwenn printers.
So Yes it is the cable.
I damaged the cable by fitting a Support Spine that was too stiff 
However: YOU CAN NOT GET A REPLACEMRNT ONE as SOVOL Just ignore you
Looks like I will have to adapt some other cable
I was able to get with the folks at Sovol and they say they are sending me a new cable. That was a few days ago. I’ll post back if I do get it.
Update. I received the cable from Sovol and the printer is back working.
Just a note for anyone having to replace this cable, the connectors inside the control box are ‘hot glued’ down. Made for an interesting time with old hands and an exacto knife!!