Help needed - enable editing in cell based on another cell value

Hi,

I have an issue here that requires help from you guys because I'm pretty bad at VBA!

- The cells in the "G" column (G4:G25) have List validation (valid values are "A" ,"B","C","D" ).
- The cells in the "H" column (H4:H25) have List validation (valid values are "Yes" & "No").
- The cells in the "I" column (I4:I25) have Normal text validation.

For service "D" selected on column "G", column "H" should be editable
Then, for "Yes" selected on column "H", column "I" should be editable

Could you help me out on this one please?