Sounds like the battery didn't run out and more likely the fob just died as they do all too often (thanks Porsche)
Lots of Boxster owners have just bought after market central locking units and wired into the doors contacts as a way of having a reliable cheap fob replacement.
Brief write up here and the kits normally tell you where to splice into:
Posted December 11, 2010 (edited)
MY97 Australian delivered car. Has driver side and passenger side keyholes. Has central locking. No remote. No alarm.
I just installed an aftermarket alarm/remote/proximity entry unit. I will write up a
DIY if there is enough interest but I believe most people from the US would have the remote feature as standard. Come to think of it, there is probably not much to write. Everything you need to know is below:
1. Everything can be hooked up under the passenger seat (RHD car) except the ACC ON signal, so remove the seat first (4 screws)
2. A Bentley manual or a wiring diagram from the factory manual is an absolute must, and contains all the necessary information to figure out which wires to splice into.
3. The door motors are negatively triggered
4. The door open trigger is labelled "door contact" on the wiring diagrams. I am unsure the difference between this and "door safe" - which also appear on the wiring diagram.
5. The door open signal is negatively triggered.
6. There is a separate trigger for "door contact" (door open) for each door, and there appears to be no combined signal. You might need an additional relay if you want your alarm unit to be triggered when either door is opened.
7. Unlock signal is labelled "unprime", and a single connection would unlock both doors.
8. A single lock signal would lock both doors.
9. The wire colours for a RHD car are: Red/Brown (thick) = 12V, Brown/Red (thin) = motor to open door, Brown/White = motor to close door, Brown/Green = (RHD) driver door status (closed), or LHD passenger door status; Turn signals = Black/White, Black/Green
10. Don't splice into the dash central locking switch (inside handle not secured), use the direct connections to the motors above
Credit to Jinster @ Rentech
https://www.renntech.org/forums/topic/36144-remote-central-locking-install/?_fromLogin=1 (you'll have to login to view)
Excample of the kit
https://www.aliexpress.com/item/Viecar-Car-Remote-Central-Door-Lock-Keyless-System-Central-Locking-with-Car-Alarm-Systems-Auto-Remote/32969027039.html?spm=2114.search0604.3.1.2c836f189fHir0&s=p&ws_ab_test=searchweb0_0,searchweb201602_2_10065_10068_10130_10547_319_317_10548_10696_10192_10190_453_10084_454_10083_10618_431_10307_10820_10301_10821_10303_537_536_10059_10884_10887_100031_321_322_10103,searchweb201603_2,ppcSwitch_0&algo_expid=b83073cc-57fd-4a02-8705-6c3a56874217-0&algo_pvid=b83073cc-57fd-4a02-8705-6c3a56874217&transAbTest=ae803_3
Remember this is not over riding the OEM alarm system its just utilising your RFid pill for the immobiliser and energising your door locks.
There are more detailed posts around if you search.
Regards
Richard.
