You could use an enamel paint for metal to make it match the walls or trim and secure it with some good brackets and long screws into studs on the walls. 

Then you could get a piece of 1/4 " thick mdf and some cheap trim and some chalkboard paint, and create a framed chalkboard that completely covers the hole from the outside.EDIT: I am an engineering manager at a cabinet and Millwork shop by day.

use a 5 in one and remove the caulk take your time and pull it out most of the time it will come out in peaces once you get the corner. when you go to lowes or home depo in the paint section with the rest of the caulk you will see it has bath and tub caulk on it. don't skip on the cost one has non srink on it and last along time .worst case you tub remove caulk form tub and see them do it and do the same thing dap is not made for tub its for base and trim for but double check that what we use it for . .

You will want a field and trim/accent colors for the house.

We've already mowed, but haven't trimmed as much as we probably should.  

I agree that a strip of J Trim at the bottom would pretty it up. 

Also, if you keep the window you should replace the any wood trim with PVC trim so it doesn't rot.  

It now has 4 large shelves with proper trim work and looks great. 

I'm assuming it's just basic cosmetic work needed to achieve those rents.Post Work CAP Rate: ~10cap (45% expenses & based on $1,222,000)The plan: EARLY WORK - 3 of the buildings need exteriors re-painted and some trim work, townhomes need new garage doors As leases expire we raise rents to as-is market valueIf tenant does not renew and moves out, we will upgrade unit and get the higher rents

I suggest the type that are Can Trim LEDs that screw in like a bulb.