This almost works except the radio buton itslef is also locked when the record is locked...therefore I cannot use the radio button to unlock the record (a solution to this woudl be most helpful!)
Use a script set to "run with full access privileges"--a check box at the bottom of your script editor to modify this field.
Use Set Field to modify your radio button field. Insert script steps will fail if the specified field is removed from your layout--perhaps that's the layout change that you made?
I'd write a "toggleLockStatus" script like this and use button set up to format your radio button field as a button to perform it:
If [Table name::Lock Flag = "Locked" ]
Set field [ table name::Lock Flag ; "Edit" ]
Set field [ table name::lock Flag ; "Locked" ]
Another option is to put the radio button field in a different table linked in a one to one relationship to the original table. Then it will not be affected by the "lock" on a given record.