Would like to save this plant.
Leaves Are Turning Brown on Geranium
Certified GKH Gardening Expert
If the plant sits in soggy soil it can develop root rot and a bacterial leaf spot.
There is little to do if this is the case.
Check watering. If the the soil is dry this can also be the issue. To little water and the leaves will turn from yellow to brown.
Here are a few links for you.