The Detonator puzzle is dependent on acquiring a number of key items scattered around East Raccoon City in Resident Evil Requiem. These items have to be either combined or repaired in order to get different parts for the Detonator.
This Resident Evil Requiem guide has the locations of all the key parts needed towards assembling the Detonator.
Distributor
Open a yellow container at the northern end of the Logistics Warehouse Roof.
Broken Signal Receiver
Open another yellow container at the northern end of the Cedarbrook Apartments Roof.
Distributor & Broken Signal Receiver
Once the Broken Signal Receiver and the Distributor are both in your possession, they can be combined together from the inventory.
Repair Kit
Open BSAA Container 02.
Distributor & Signal Receiver
Once the Repair Kit and the Distributor & Broken Signal Receiver are both in your possession, the latter will be repaired through your inventory.
Relay
Open yet another yellow container at the northern end of Willis Tower.
Detonator
Once the Relay and the Distributor & Signal Receiver are both in your possession, they can be combined together from the inventory.
Those are the locations of all the key parts you will need to assemble a working Detonator in Resident Evil Requiem.