How To Troubleshoot Musical Keyboard That Won't Power On?

Hi, all, new to this forum!

What is the proper sequence when troubleshooting a musical keyboard that will not power on (either by DC batteries or AC wall current?). What should I suspect and where should I start my testing?

Thanks!

(Oh, if this has been answered in another post, I apologize, and please redirect me there!)

First thing I would check would be to see if the power supply is putting out anything (the power supply circuitry internal to the unit). Ain't nothin' gonna power on without that.

Would also help if we knew what make/model the keyboard in question is.