If you want to activate the editor for a certain cell, make sure that you have a current cell (current row and current column). Then you can call the RadGridView.BeginEdit method.
In case you need further assistance please provide me with more details about your actual scenario.
I hope this helps. Let me know if you need further assistance.
Regards,
Dess | Tech Support Engineer, Principal
Progress Telerik
If RadGridView is not read-only and the editing process is not cancelled either by handling the CellBeginEdit event or by using BeginEditProgrammatically, it is possible to enter edit mode by pressing F2. By default, RadGridView starts editing a cell when clicking on a current row. So, you should first make the row current by single click, and clicking a second time on the same row will start the editing process. I have attached my sample project. Please give it a try and see how it works on your end. Am I missing something? Could you please specify the exact steps how to reproduce the problem?