With the camera in Auto Mode, A+, CA, or any other automated shooting mode (Basic Zone) the speedlite will display "locked". What kind of batteries are you using alkaline or rechargeable batteries. Rechargeable AA batteries often look like they're the same size as alkaline AA batteries. They are not the same size and are not the same voltage. Most rechargeable AA batteries put out 1.2 vdc but alkaline AA batteries put out 1.6 vdc. This will make the speedlite see this as dead batteries and not power up because of the lower voltage. So try alkaline AA batteries to see if that problem goes away. What camera do you have the speedlite mounted on. If its mounted on an EOS Digital SLR released in or after 2007, an EOS M or EOS R series camera. The External Speedlite Control Menu will be available to make changes to the speedlite's settings from the External Speedlite Control Menu. You should be able to make changes to the speedlite's settings from the camera on a compatible camera. If you can't there's a problem with your speedlite. I own the 600EX II-RT speedlite and can make all setting changes from the External Speedlite Control Menu. Older speedlites such as my old 550EX I cannot make changes from the camera's menu system. I have to make setting changes from the speedlite's LCD screen.
-Demetrius
Bodies: EOS 5D Mark IV
Lenses: EF Trinity, EF 85mm F/1.8 USM
Retired Gear: EOS 40D, EF 50mm F/1.8 STM & EF 70-210mm F/4
Speedlites: 420EX, 470EX-AI, 550EX & 600EX II-RT
