Recently upgraded to 4.2.7 board. Turn on and get beeping and no screen. Connect to computer same thing. I have gone over all wiring, connected. Blue light flashing on motherboard when turned on.Ender3pro stm32f103.
Hi @John_Burns
Welcome to the Creality Forum community… 
Just wondering if when you get a new board does a new voltage switch (120/240 V) come with it…?
Check if it’s on the correct voltage… Just checking…
Wouldn’t the voltage switch be on the PSU?
Double check that you have connected the correct wires to the correct sockets?
@Bonfireman …You are right. It should be. I’m just throwing out things to check… I’ve seen that voltage issue pop up before…
Tried reflashing the board with latest firmware?