Flight Crew Total 8431; Flight Crew Type 2569
Deviation / Discrepancy - Procedural Hazardous Material Violation; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Human Factors; Procedure
We arrived at the aircraft and were informed that on the inbound segment a passenger had lost a cellphone and it was behind a panel in the cabin. Maintenance in ZZZ was planning to defer this and send us back to the mainland with the phone lodged in whatever location it was in. After a brief discussion the Captain and I both felt this was unacceptable due to the risks posed for a Li-ion battery fire. We could not ensure the phone and battery would be safe from damage where it was and if it caught fire might be impossible to extinguish or retrieve to put in the fire bag as provided. All of this was magnified by the fact that we'd be close to 3 hours from any suitable airport should this occur at the critical point. We insisted the phone be located and retrieved before departing on the ETOPS segment. To me it seemed counter intuitive to having all this training on Portable Electronic Device (PED) fires; providing us with gloves and bags to store devices should they catch fire; but insisting that we launch across the water with no nearby diversion alternates with a PED that could not be retrieved or dealt with should the worst case occur. Maintenance ultimately found the phone and we departed.
First Officer reported  a passengers' cell phone became lost in cabin on inbound flight creating a potential fire hazard. Maintenance ultimately retrieved prior to departure.