Fix & Enhance Existing Android Java App – Bluetooth Printer, Break Timer

I have an existing Android application written in Java. The complete Android Studio source code is available and the application is already working in production.
I need an experienced Android Java developer to make several specific fixes and small enhancements. This is not a new app development project.

Main tasks:
1. Bluetooth thermal printer compatibility
- Existing NETUM NT1809 printing must remain unchanged.
- Add/fix support for a PT210 ESC/POS Bluetooth printer.
- Main issue is formatting/font behavior of the Defect Tag, Minus-Carton Tag.
- Physical printer testing may need to be coordinated with me.
2. Fix EXTRA carton status
- EXTRA status currently carries over to following inspection records.
- EXTRA must belong only to the applicable record/carton.
3. Prevent report file overwrite
- Existing SMB upload can overwrite an existing Excel report.
- If filename already exists, automatically create -01, -02, etc.
4. Upload report is only an icon, add word: "upload report"
5. Fix/refactor Pause/Break function
- Correct pause timing and Cancel behavior.
- Support more than two pauses.
- Pause must survive navigation between activities.
- Correct handling of pauses longer than 59 minutes.
- Break reason and Excel/report output must remain consistent.
6. Logout completion check
- Before logout, check whether planned inspection quantity/tasks are completed.
- EXTRA cartons must be counted separately.
- Show completion summary or incomplete-plan comment prompt.
7. Configurable SMB folders
- Allow separate configurable subfolder/path for Plan Download and Daily Report Upload.

Important
A detailed source-verified change request will be provided. It includes existing methods/code areas, required behavior and acceptance tests.
I am looking for someone who will modify the existing application carefully, not rewrite it.
Existing unrelated functionality must remain unchanged.

Deliverables
- Updated complete Android Studio source code
- Working/signed test APK
- Short list of files/methods changed
- Regression testing of the requested functions
- No source code obfuscation or dependency on the developer after completion

Required skills
Android Java, Android Studio, ESC/POS Bluetooth printing, SMB/file handling, SharedPreferences, Excel/JXL handling, debugging existing applications.

Please bid only if you are comfortable working with an existing Java Android project.
When applying, please briefly describe your experience with ESC/POS Bluetooth printers and debugging existing Android Java applications. Generic copy/paste proposals will not be considered.