Hi Brock,
thanks for the lead - unfortunately that's for the Garmin Nuvi 660, at different model altogether, but it did give me a lead to the Zumo 660 videos.
The Zumo 660 has it's battery cover panel on the left hand side (from the rear) with the panel's slide key underneath on the lower edge of the unit.
Opened the battery compartment, removed the battery that allowed access to the micro SD card.
Removed the card and replaced the battery then replace the battery compartment's panel. Pressed the on-off power switch down as usual.
Held the switch down for 8 second first as per the instruction, then for a good 30 seconds, again nothing at all on the screen.
Released the switch and repeated holding it down again, just in case it was in the 'on' position to start with, again nothing.
Checked the owner's on-line manual.
Under 'Trouble shooting' (page 44) there is nothing at all about not being able to turn on.
The only piece of useful information was to check the 'fast-blow' fuse inside the automotive cigarette plug.
Did that, multimeter showed the fuse is in perfect condition.
Also tried the instructions for the 'Resetting the Zumo' and the 'clear all my Data' - with the mini SD card removed - again nothing happened at all.
That is the total limit of any sort of trouble shooting in the owner's manual.
It's obviously written with the USA market in mind attitude, ie - " You're too stupid to be told any more. Send your toy back to us to be fixed or throw it away."
In today's world there's also the - "We're not going to tell you anything more in case you decide to sue us. "
Next step, phoned 'Battery World' to get a quote on the cost of a replacement battery.
GREAT ! They only list batteries up to the Garmin 550 model.
The guy from Battery world suggested bring the whole unit to their shop and they'd physical have a look at it and see if they have a compatible battery available.
So, still looking for an authorized Garmin repair business somewhere hopefully in the Perth metro area.
Seem to remember when I first purchased this unit, there was a place somewhere north of the river - out Balcatta way somewhere. ( I think )
Thanks again for the lead, Brock.
Back onto the Google machine again for a while tonight.
Flip.
STILL no YAROOOOOOOOOOOOOOOM ! (YET)