Have you called the dealer and asked the service
department yet?  That would be my next move.

You could try destroying the bonnet with various demolition tools.
Or you could CALM DOWN a bit and call a Porsche service tech.. other
thoughts - I've seen flat battery starters that are supposed to work via the
cigarette lighter. The idea is that you plug it in, then turn the engine
over. Now, you say you've tried charging the battery, but have you tried
this?

Finally, sit down, have a nice cup of tea and seriously consider why any car
in the entire universe might need a motor-operated bonnet release. It's
absurd! Surely there has to be a manual override somewhere? Does the owner's
manual give any clues?

Chris.

HI,

Ive got the flat battery access sorted on my Boxster and your're right
about no power point for powering the battery up from outside the bonnet,
unbelievable i know, but you will be glad to know that Porsche has now a
powering point for the battery on all Boxsters produced after 2002 located
at the fuse box on in the righthand foot well.

Anyhow i got an ex-Porsche tech to call out to the house & he had it
opened in no time, i had already contacted my local Porsche dealer but
they had offered a few suggestions of how to gain access, but not the one
this guy used, he removed the three screw covers on the lever housing then
with a 5mm allen key he undone the three screws lifted the lever housing
and pushed done the switch located below the boot and bonnet levers and it
was open!

I feel that the local Porsche dealer may have know about this way to open
the bonnet, but would much rather charge me to recover the car from the
house then hit me with a bill for a few hours labour to gain access to the
battery and then fit a new battery to top it off, so now everyone knows
how to avoid this and save themselves a lot of money.

Thanks to everybody who offered their advice and support on this matter, i
hope it will help someone else unfortunate enough to have the same
problem, thanks again.