After attempt to connect to a Bluetooth address for a peripheral that just powered off (battery died), central can no longer connect to any other powered-up peripherals. (This would occur if central scans for and detects peripheral, but peripheral then is powered off before central connects to it.)
Peripheral with Bluetooth address '000000000001' is powered on, and peripheral '000000000002' is powered off.
Central connects to P1 okay and gets notifications. Then disconnects.
Central tries to connect to peripheral '000000000002'.
Central disconnects.
Central tries to connect to '000000000001' again, but does not even get the connUp callback.
Why can't central re-connect with peripheral '000000000001' ?
Solution is to scan for the peripheral first, and only attempt connection if peripheral is NOT dead.