Generic Battery? Car is dead..

[Brucelee]

Any replacement battery is fine. Costco and Kragen have batteries for around $60.

[blue2000s]

If you first take out the battery and bring it to an auto parts store they will test it for you to see if it's your problem. That's free and will save you from replacing something that may not be your problem, although it does sound like it might be your problem.

[Norminhouston]

Sounds like the ignition switch is bad. Repair is easy. Part # 4AO 905 849 available from ******************************** AZ for about $11. A common problem with Boxsters. I always carry a spare.