Android app Developer -Fix bugs/U.I design and integration

PichApp ------------------------------------- I hired a freelancer here 3 months ago to work on my photo ordering app which I launched two months ago on google play. It has been downloaded by a couple of customers but it crashes on some phones especially android 5.0 and later. Also, it does not work on tablets. Another issue is that U.I design is not that appealing. These are the things I need fixed. You can find the app on the link here on [login to view URL] I need a developer to; 1. Help me design a better UI interface with nice and catchy login screen with options to login with facebook and google plus. 2. Fix bugs- At the moment, when I open the app on my phone, the login link is not visible. Note: I don't have the source codes, so I am looking for a developer who can unpack the app from the Google store and continue from where the other developer left. Apply only if; 1. You have done same kind of work and believe can come up with appealing design. 2. If you can do this job for me for $100 3. You have good communication Skills. 4. you are interested in making my business successful and customer friendly. 4. Have better advise for me on the best features to add on the app to make it sell out. This will be a continues job for the right candidate. I will be needing more features integrated on the app. In you application indicate links to some examples of work you have done in the past.