Bluetooth dies on Logitech MX Ergo

Logitech MX Ergo trackball, purchased early 2019, 1 year warranty.  Bluetooth initially worked.  Then used for a while with USB wireless dongle.

In late 2020, tried Bluetooth again; it no longer works.  Seemingly its Bluetooth radio has died, unable to be seen from many Bluetooth computers after putting in pairing mode by holding down the center button until the number flashes rapidly.

Complaints that Logitech products have planned obsolescence seem justified.