BetaSX deck issue

Does anyone remember the SX compact editing system? I am trying to fire one up for the first time (the DNW-A220) so that I can recover some footage from BetaSP camera tapes (before they fall apart).

The V-Mount Sony power supply (model AC-DN2B) starts up fine, with cooling fan humming away, but the VTR itself will not light up. I've tried the power supply both with and without the additional 4-pin short jumper cable, but it makes no difference. The screen and VTR in general do not light up.

I'm pretty sure I am dealing with the player unit of the 2 - this one has the switch that allows for choosing between SP tape and SX tape.

Any hints as to what I am overlooking? Could the VTR itself have another power switch hidden? I have found the manual for this unit, but did not find anything useful within.