Help — installing an APK

1. Download the APK

Pick a version on the app's page and tap ⬇ APK. Your browser may warn that the file "can harm your device" — this is the standard warning for every APK, not a sign of a problem with the file. Check the SHA-256 shown next to the download link against your downloaded file (step 4) if you want to be sure.

2. Allow unknown sources

APKs installed outside the Play Store need one extra permission:

• Android 8 and newer: Settings → Apps → Special access → Install unknown apps → your browser or file manager → allow "Install unknown apps".
• Android 7 and older: Settings → Security → tick "Unknown sources". Turn it off again after installing.

3. Install

Open the downloaded file from your notifications or file manager, tap Install, and open the app. If your phone says the app was built for an older Android version, pick an older version of the app from the version table instead — that is exactly what the "Android needed" column and the filter dropdown are for.

4. Verify the file (optional but recommended)

The checksum next to each download lets you confirm the file is the original:

• Windows: certutil -hashfile jkbms-4.2.1.apk SHA256
• macOS / Linux: shasum -a 256 jkbms-4.2.1.apk
• Android: file managers such as Solid Explorer can show a file's checksum.

The result must match the full SHA-256 shown under the checksum on the app page. If it does not match, delete the file.

5. Troubleshooting

• "App not installed" — the version needs a newer Android than yours; check the filter dropdown.
• "Parse error" — the download is incomplete or corrupted; compare the checksum and re-download.
• Bluetooth can't find the BMS — grant the app Location (Android ≤11) or Nearby devices (Android 12+) permission.