Comment by femto
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.
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?