Dead Cetus Mk3 with extension board

I have a problem with my printer.
It dosn’t connect via USB and dosn’t initialice via the Butten on the Front.
The Led is shining blue constantly and the Fan is running
a extention board and Heating bead is installed

Have you followed this updated guide? - https://support.tiertime.com/hc/en-us/articles/360023111253-Detailed-Guidance-on-Extension-Board-Installation-and-Limited-Switch-Issues