It is still a rental property as long as it was available and advertised for rent during 2020 (the fact that it wasn't rented will not make it a personal use second home). You will just put "0" for question on "the days rented at FMV" if only available to rent but not rented.
Please note that the days that you worked on the home as not considered personal use days. Your capital improvements will increase the basis in your property.
If you were not marketing the home as a rental or attempting to rent it out, them it is no longer a rental property.
Rental expenses can be deducted from the time the property is made available for rent. The expenses incurred and paid in connection with managing and maintaining the property while it is vacant are deductible. However, you cannot deduct the loss of rental income during the period in which the property is vacant.
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Real Estate Tax and Rental Property - TurboTax Tax Tips ...
