Speedlite 600EX-RT won't unlock

[lhardaker]

I need help unlocking my Speedlite.  I have a lever off/lock/on - whether it is in the locked position or the on position, it disallows any other settings as it states it is locked.  #speedlite#  Help

[deebatman316]

What mode are you shooting in this makes a difference. Also when you say lever do you mean the lever that locks the speedlite in the hot shoe. Or the physical power switch that says Off, Lock, On. 

[lhardaker]

It doesn't matter whether the flash is on camera or off camera.  I'm referring to the physical power switch that says off, Lock, On.  The unit also will not power on unless the switch is in the on position and I open then close the battery compartment.  Very odd behaviour.

[deebatman316]

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. 

[lhardaker]

I'm using Energizer Max AA alkaline batteries.  Brand new - tried two different sets of them.  On camera or off camera doesn't matter.  It displays "locked" even when the physical switch is NOT in locked position.  I use(d) it with a Canon 7D, post 2007, but when mounted on my camera, the camera says there is no external flash located.

I had an issue with corrosion as the unit had been left with batteries in for too long.  I spent a lot of time cleaning all the corrosion from the terminals.  Is it possible that there is corrosion inside the unit itself?

[deebatman316]

There is a problem with your Speedlite so contact Canon for repairs. Get a quote first if they can repair before repairing it.