Advice Needed: Mortgage assumption on rental property?

First time poster here. So, I just evicted my long-time tenant and she's left the townhouse a complete mess. It will cost ~20k+ to repair. The guy that I was originally going to hire as my new property manager for future tenants has offered to do a mortgage assumption. Between mortgage and heloc, I only have about $30k equity in the property.  What should I do? Take another loan to fix up the place and keep it or let it go? Any advice is appreciated!