Service Mode entry
Had an SC500 roland which went like this, maybe this is it.
-first the "S" by pressing: top,left,right,bottom
-then the "V: by pressing: left,bottom,right
-last you hold down: left,bottom,right --->before letting up press pwr button.
The idea is "S" for Ser and "V" for vice - in other words Ser vice.
I know this is the new service mode entry when using the current firm ware
for my SC-500 roland.
Hope this works out.