>My understanding is that they were extremely well concealed
Source? I'm not sure how you can concealed any meaningful amount of PCB/explosive in a pager/radio, unless you're hoping that your target never opens the plastic casing, or doesn't know what the internals are supposed to look like.
From the picture it looked to me like it was more aligned with the DAC, although I double checked and I don't think that any DACs of that size would be in the order of 20-30 grams. Could a discharge be angled like that within the confines of the can?
The most plausible theory seems, that the batteries were manipulated/replaced with smaller ones, from the outside still looking like normal batteries, but with explosive inside.
So a shorter battery life, but usually no one cuts open batteries.
(But now some will start doing it)
If you had a known good copy, should be able to differentiate on an X-Ray.
Weights might not be right either but they maybe they corrected for that.
Centre of gravity may have changed.
You know what a LiPo pouch looks like right? silvery bag, some yellow tape at the end with some wires sticking out.
Less likely you know what they look like inside, as it's been drilled into us not to pierce the things. Also if your laptop battery only lasts a couple of hours you might suspect something is wrong. If your pager needs recharging every month instead of every 2 months... well nobody has a clue how often a pager should need recharging.
I've no idea if it was the battery, but just feels like the right approach.
Looking at this picture (assuming it's of one of the actual radios):
https://static.independent.co.uk/2024/09/18/17/walkie-talkie...
and a picture of the main board on page 5 of the Icom service manual:
https://www.slideshare.net/slideshow/icom-v82-service-manual...
I'd guess the explosives were inside the "VCO can": the metal shielding around the VCO circuit. The picture of the radio shows the radio's metal casing bent away from the PCB, suggesting the blast came from that direction rather than the battery. The VCO can would have air-space inside it and is unlikely to be opened, even by a service tech. There will be an SPI serial bus running from the CPU into the VCO can, to allow programming of the VCO, which could be used as a conduit for a trigger command.