Printer will not power on after upgrade to MK3S+
I completed the upgrade from MK3S to MK3S+ but this also included replacing the hotend assembly with an E3D.
I connected the printer to power and flipped the switch and the screen does not come on and nothing happens except I noticed the red light is lit on the extruder.
I started by checking all the cables and there was one fan cable not connected but even after connecting that the printer would still not power on. I reviewed various guides and confirmed all the fuses are still good AND the PSU's light is green.
Any ideas on what I can try or what might be going on?
Thanks.
RE: Printer will not power on after upgrade to MK3S+
Have you checked the fuses?
was the new hot end 12 volt or 24 volt?
A common error is putting a 12 volt heater on a 24 volt printer, this draws so much power that it blows the fuse. 
the attached chart shows 12 volt heater on 24 volt printer (Mk3 series)
and
24 volt heater on a 12 volt printer (Mk1 and Mk2 series)
Neither result is good, but 12 volt heater on 24 volt printer does more damage...
the resistances for the heaters are shown in the chart. if the fuse is not the issue, check for continuity and resistance with a multimeter.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK