It’s also the most unlikely explanation of all, that phones brought in communicated with the ones in custody to reboot them. Even if it was a security feature to reboot phones under certain conditions, which is very likely TBH graphene OS does this, the best implementation isn’t going to be relying on other phones randomly passing near by, it’s going to be self-managed by the phone that reboots.
2 x 8tb HDDs is roughly $200USD
I don’t know what kind of electricity prices you’re paying, but to hit a 3 year ROI on your SSDs, you’re paying at least $2.2USD/kWh, assuming the full 15W (232kWh/year total) consumption of the HDDs and assuming negligible power consumption from the SSDs.
Edit: average power consumption for HDDs read/write operation is usually around what you claim them to idle at, with actual idle consumption below.
Edit2: and to be fair I did take refurb HDD price. a refurb SSD is around $300 USD for 8tb, bringing the minimum power cost per kWh down to ~$1.7USD/kWh for a 3 year ROI.