I can't write a sleep mode to an XBee via XCTU. Is the device damaged?

XBee & XBee Gateway
1

I can update the firmware. I can read/write other parameters. The Xbee is currently in SM 1. I can set it to SM 4. If I try to set it to SM 0, I get a write error. The Xbee device is a XB24-ZB, ZigBee End Device AT, version 28A7

2

That is because Digi’s implementation of an End device requires it to sleep. So trying to turn of sleep is not an option. Not without making it a Router.