Lift up the ADF ( doc feeder and) and turn on the copier, look at the scanning unit ( light that comes across the doc) is it stuck ? does it try move and give a code ?
check for a loose sensor, it may not know it's in home position
there is a fuse if I remember on the left side of the unit, remove one screw and check for continuity.
i misplaced my manuels and this error message is now comming up on my copier . my copier is about one year old now
KONICA 7020 GIVES ERROR MESSAGE F-35-1O WHAT IS WRONG