IOS 11 Bluetooth connectivity - known Apple issue across many Bluetooth devices. Please update your iPhone to the most recent iOS 12 version which resolves the issue entirely.
If you are using an iPhone with IOS version 11 , when the POWERUP module is turned on (LED blinking twice every second) and the app keeps "searching":
Restart your iPhone! (temporary solution until you upgrade to iOS 12 newest version)
If you still can't connect, please work through the following steps:
1. Go to the iPhone's settings and make sure that the Bluetooth is turned on.
2. Slide up the iPhone's Control center make sure that the Bluetooth is turned on.
3. Double-tap the home button and kill the app. Open the app and wait a few seconds for connection.
Another way to fix a connection issue is to reset your iPhone's network settings. Settings > General > Reset > Reset network settings.
* This last action will erase all your saved network data including passwords.