From when to consider that my h1b visa is denied?

Hi,

On March 30, when I verified USCIS portal, I came to know that my H1b visa got denied.
I will be completing 240 days on April 12th.

I applied to I539 B2 COS due to corona virus on April 11th saying that I did not yet receive status but I will be completing 240 days of my visa, so please change my status to B2 to avoid unlawful status.

Did I do any mistake by saying that I did not yet receive status? because my employer did not send the denial notice to me yet by April 11th?

Also is it okay to mention that I will be in unlawful stay by saying that I did not receive status?