Locking a row based on a cell value in a cell in that row

Question

Dear All,

I have read many posts on how to lock a range of cells based on a value on a specific cell, but none helped me.
I am having a spreadsheet where multiple users are filling in values in it.
I would like that if a value at the end of a row is filled (with any value) to lock the editing possibility to the rest of the cells in that row.
The solution should leave "editable" rows that do not have anything filled in the respective cell.
For example, in the row A1:O1, there are some values filled in (some cells might be empty).
When I am filling a value (any value) in cell P1 (the last cell in that row), the entire row should be blocked for any further editing.
Any other rows, if they do not have any value already filled in the cell P..., should be available for editing.

I have to add that I am not familiar with VBA.

Thanks in advance