Do these steps and let me know if the WordPress for Android Mobile App works or not.
1. Use FTP or your web host control panel file manager and delete the root htaccess file (in the same folder as your wp-config.php file) and the wp-admin htaccess file.
2. Deactivate the BPS plugin on the WordPress Plugins page.
3. Test the WordPress for Android Mobile App and see if you can now access your website.