Hi Mary,If you haven't found a solution yet, I am currently building an app that has a maintenance tracking feature and maintenance reminders are next in the pipeline. 

Does anyone know of a free mobile app that i can use to scan receipts, until i can generate funds to  purchase quick books?

You can avoid the firmware issue by taking your phone in close proximity to the lock (a few inches or less) and use the app to check for any firmware updates.

I'm just looking for a good app that can help me record receipts and expenses, help me management income. 

Quote from @Robert Leitner: I have a couple properties and use Stessa as my property management app but they don’t yet have maintenance and issue tracking.

Quote from @Purva Raichura: You’re right: serious developers don’t replace pre-app meetings, civils, or title services with software.

Quote from @Jake Baker: @Tony MuratoreAccepting rent through payment processors like Venmo, Cash App, Chime, and Zelle can complicate the bookkeeping. 

Some common names you'll see thrown around a lot: Stessa, Apartments.com, RentRedi, TenantCloud, Innago, RentManager, Avail, Rentec Direct, Doorloop, etc.I recommend you search for each of those apps online and see what they offer, how much they charge, etc.

I use the RESPtracker app.

There are many apps you can use, but I prefer the old school way.