iPhone won't sync with JBL flip anymore

Hello, upon scanning old trees about this issue, I have seen many other people with this problem from years ago, but from what I could tell no one was correctly preparing the JBL flip for sync, and once they understood how to do this their problem was solved. I'm having more of a complex issue, where all things appear to be working to facilitate a sync, but it never works. For instance, I go through the steps to get the JBL Flip power button to blink blue (which indicates it is ready to sync). My iPhone recognizes the device in "other devices" under the Bluetooth section of my phone's settings. However, when I select "JBL Flip" to pair/sync the spinning indicator spins and spins and eventually gives me the same error message time and time again: "Pairing Unsuccessful. Make sure "JBL Flip" is turned on, in range, and is ready to sync." I have used JBL bluetooth speaker for years (with this very same iPhone) without problem. Suddenly last week it stopped being synced and just won't reconnect. What can I do?