I watched some random YouTube videos on someone talking about digital cinema units, so this is all second hand half-remembered knowledge, so take it for what it

I watched some random YouTube videos on someone talking about digital cinema units, so this is all second hand half-remembered knowledge, so take it for what it's worth. From what I recall, the security module has it's own battery backup, intrusion detection, etc. If the module detects tampering or it's battery goes flat, the keys are wiped. There was some talk about that you can't keep "spare" security modules hanging around, they need to be installed in a projector periodically to recharge the onboard battery.