Dead battery, yes I read the posts...
 

before asking. Came home from a long business trip and noticed the window would not crack when I tried to open the door. Oh oh. Anyway, borrowed a trickle charger from a friend and pulled out the charge socket in the fuse panel and connected the ground side to the hinge on the front door (charger said battery not charging). put the negative on the seat rail (not charging) and on the door striker (not charging).

so my question, can you use standard jumper cables on the post and ground (and BTW what is the best ground point?)? Any other ideas? Gotta get the front hood open so I can address the battery.

As always, thanks in advance!!

You tried to open the frunk with the trickle charger hooked up?

I doubt a trickle charger can provide enough amps so perhaps another 12v battery, jump from another car to the fuse pop up terminal or a regular charger that can supply at least 6 amps to get the Frunk solenoid to pop the hood open. Your ground points sounded ok, but an unpanted connection is necessary, like a bolt/nut.

Jumper cables are fine

Your battery might have an internal short. Once a regular lead acid battery is run completely flat due to some power drain, the chances of it being revived are low. Usually a new battery is required.

by trickle charger, if it's "battery tender/charger".the one that I have will not charge battery if it's voltage is less than 10V. did not know this and thought the battery tender was also bad. With the battery tender connected, i jumpered a radio controlled car Lion charger. This pulled up the boxster battery high enough for the battery tender to initiate charging.
I ended up replacing the battery after similar problem the following month.
My bottom line is that if battery tender can not initiate charging, it's an indication that the battery is at end of life (or bad).
side note: the cigarette lighter is always connected to the battery (fuse in series). I used one of many old cell phone car charger (the portion that plugs into the cigarette lighter socket) to connect to battery tender. if the car is going to sit for a week or more, i just connect battery tender via the lighter.