B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP); Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Type 3681
Time Pressure; Situational Awareness; Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
General None Reported / Taken
Company Policy; Procedure; Environment - Non Weather Related
[We] arrived at [the] gate. Ground crew did not immediately hook up ground power. We had ground time before [our next] flight so after configuring the aircraft; IRS's; ACARS; and FMC's; I went into the terminal to use the restroom. Upon my return; I found the APU shutdown; auto brake fail light illuminated; and brake hydraulic pressure indicating zero. Further investigation revealed the IRS's shut off; fuel pumps shut off; battery shut off; emergency lights shut off; and window heat shut off. A call to Maintenance inquiring if they had been in the cockpit revealed the APU shutdown team had connected ground power and shut down the APU along with the other configuration changes.Why was the IRS's turned off as part of an APU shutdown? Why were the fuel pumps turned off as part of an APU shutdown? Why was the battery switch turned off as part of an APU shutdown? Why was the emergency lights turned off as part of an APU shutdown? Why was the window heat turned off as part of an APU shutdown? None of these systems needed to be reconfigured to turn off the APU; nor would the flight crew expect them to be changed as part of the APU shutdown; especially when the aircraft was not terminated.The cockpit was clearly occupied and prepared for the next flight as evidenced by personal items; iPads in holders; and paperwork on the center console. The configuration changes were beyond what is required to shut down the APU. Without notice that anyone has made configuration changes; there is serious potential that we could depart with an undesirable configuration and a potential safety hazard. Additionally; with the battery switch and emergency lights turned off; if an emergency had occurred during boarding but before the flight crew returned and discovered the altered configuration; flight attendants would have no public address or emergency lights. I am familiar with the FOM requirement to review aircraft configuration after maintenance work. However; without any maintenance work there is no reason to review the aircraft configuration.
B737 First Officer reported that after setting up the cockpit prior to flight; someone came in the cockpit and undid the set-up configuration.