It seems that this rear cover is simply a method to connect the module to power.
The spring and lithium cell look suspiciously like an active tamper-awareness mechanism to me. I can think of two good reasons for tamper-awareness.
First, a savvy EE might disassemble the device in vivo and replay innocuous trip data briefly while engaging in mischief. This kind of attack is better than disconnecting the Tx antenna or moving the transceiver to a different car because it will be very difficult for the FBI to detect that the trackee is on to them. Sending a patrol car once a week or month to look for the tracked car at the reported position would quickly reveal that the device had been moved, as would correlation with any other observations like electronic toll data.
Second, if as commenter Robin speculates, the FBI's receiver is listening to the more accurate encrypted GPS signals, in vivo disassembly might allow disastrous compromise of the cryptographic material necessary to do so!
Quando lo avranno fatto, sarai in grado di visualizzare un grafico della reputazione guadagnata nel tempo da loro.
Ecco un'anteprima di come il grafico apparirà:
Ancora nessuna reputazione acquisita.