Bolt IoT app is designed for Bolt version-2 (White color Bolt). You can not use that app for setting up the Bolt version 1. I think there is some problem with your SD card. Format the SD card and copy the Bolt -SD- Card file from github https://github.com/Inventrom/bolt-sdcard-files and paste it to root directory of SD card, means when you open the SD card, all the files should be visible without going inside any folder and then change in bs.txt file.
Do let me know in case you need further assistance.