Rebuild EMI Locking DPC App

I already have an Android Device Policy Controller that locks financed handsets when an EMI is missed, plus a small web dashboard that lets the lending team provision devices and trigger unlocks. The current build is unstable on Android 13, the UI feels dated, and the payment workflow is tied to a gateway we no longer use. I need the entire solution rebuilt and hardened.

Core behaviours that must work flawlessly:
• Lock the phone the moment a scheduled payment fails.
• Allow me to whitelist only basic apps (dialer, messages, payment app) while the device is locked.
• Push automatic reminders before the due date and after a failure until settlement.
• Capture an e-mandate (eNACH/UPI AutoPay) during onboarding so future EMIs run without user action.

The admin portal should let me create a customer record, push the DPC during device setup (QR or NFC provisioning), set or edit the repayment calendar, view real-time compliance status, and manually override a lock if support approves. Please keep the API layer clean so I can later plug in analytics.

Tech stack is flexible, but you must already be comfortable with Device Owner APIs, foreground services, FCM, WorkManager, and a modern payment gateway that supports e-mandate (Razorpay or Cashfree preferred). The existing code is in Kotlin and React; reuse whatever speeds you up, but I’m fine if a fresh codebase gets us a smoother outcome.

Acceptance will be:
1. APK installs as Device Owner on Android 8–13, passes all scenarios above, and survives reboots, factory resets blocked.
2. Portal deploys on my AWS instance with SSL, role-based access, and logs every policy action.
3. Clear, buildable source plus setup notes so my in-house dev can extend it later.

If you’ve shipped DPCs or MDM features before, tell me what provisioning method you’d choose first and how long you’ll need for a pilot build.