have you tried taking everything else out of the case - except minimal modules you need to test the sinfonion with?

just to double check - when you 'checked' the power - you checked that the power cable was correctly made as well as inserted correctly at both ends

what case/power is it?

what else have you in the case? - post link to public rack url

"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia

Utility modules are the dull polish that makes the shiny modules actually shine!!!

sound sources < sound modifiers < modulation sources < utilities