Calculate the discounted cash flow for a real estate; find if I should sell or keep renting or renovate and keep

This real estate was made for their employees to live in. There are 50 units. they have bought these units for 12.8M USD back in 2003. the market value of the real estate was 25M USD. The market value for the real estate now (2021) is 40M USD. these units are very old and the Company XY don’t know if they should sell these units or make a renovation or keep it as it is. The income for these units is 2.8M USD. The maintenance cost is 1.7M USD. if the company choose to renovate they will renovate 5 units per year for the next years with the cost of 250K USD per unit. there is an additional cost of 800K for manpower.
Please send the DCF for each year and use 9% discount rate for the above case.