Analogue-sequencer

> I turn it on with 
> F1+7 (how big are your hands anyway!?)

Not quite big enough to hold that combination by accident, which is the
general idea.
You don't have to hold it right at the instant of power-on - it scans for
those keys after the first LED colour cycle.
So you do have time to power-on, then hold F1+7.

> and was asked whether I want to 
> clear data or cancel.  F1 (clear) doesnt seem to respond..?

[ clear ] requires both F1 and F2.
This approach is intended to prevent someone who finds themself attacked by
an alien creature just as they turn on their P3 from accidentally wiping all
their pattern data while rolling around on top of their equipment, trying to
release the creature's fearsome reptilian strangle-hold.

> I try again and same.  Now whenever I power 
> up, all that happens is the 8 mode leds light up for a second and go 
> off and then it sits there looking dead.  When I flick it off 
> from this 
> frozen state, the pattern leds flash for a tenth of a second as does 
> the PLED which reads <<P3 Sequencer>> for that tenth of a second.

That's certainly not normal.
Does it boot into the firmware upload mode OK ?
Hold FUNC+PAGE at power-on (right at power-on this time...) and see if it
gives you the image checksum and boot/flash options.
 
> If it matters any, I powered it up yesterday with the ram backup IC 
> (1210 iirc) in backwards a few times before I saw it.  Could this be 
> fried?

I've done that myself, and it didn't fry. No guarantees though.

Cheers,
Colin f