These directions assume that you have the XBee module already added to your Digi Remote Manager account and that the module is configuured to be connected to Digi Remote manager via its AT commands more than once every 24 hours. If this is not the case, please see the AT command section of the XBee Cellular modules Product Manaual.
From the Main screen of Digi Remote Manager, on the left, select the menu > Management > Devices.
On the Devices screen, put a check mark on the left box of the device you wish to update.
On the right, select Actions > Update Firmware
In the Update menu, select the desired firmware version. Select the Update button on the top right.
The menu will then display a progress bar indicating how far along it is in the process. You can verify this has been done by reading the devices settings either from Digi Remote Managers Device Settings function, Digi XCTU or the Digi XBee Studio.