A couple of points for you:
- Yes you short the battery with the power off, two or three seconds should do it, if you short it for too long you risk damaging the battery.
- A sammy will set its own netid in Langley (pure NTL) areas ONLY if it has Langley firmware installed. Your Poole box will be Bromley (exC&W), and I'm pretty sure the Fareham one will be too. You can check this by looking at the top of the last page in the engineers menu - the firmware version will be something like 3_2Lxxxx (Langley) or 3_2B (Bromley). This is not a problem, it just means you have to set the netid manually (either via jtag or funcard). As soon as the box is connected it will then take a Langley update and from that point on it will behave as a Langley box (e.g. if you reset the netid again, it should subsequently auto-detect).