Bluetooth keyboard not connecting

My rocksoul bluetooth keyboard no longer connects with my MacBook Pro running Catalina. Bluetooth is on. The device is discovered. A PIN is requested. I enter the PIN in the keyboard as requested. It thinks for awhile, then returns the error "Couldn't connect to the device".

I have restarted the Mac. Turned the keyboard off and on. Checked the batteries. I keep getting the same error (pic attached).

Youtube link to video showing problem: https://youtu.be/8sORVfCkz70.