If I need to do an over the air update of a very remote sleeping Boron, what is the procedure to wake the device and download software?
There is no procedure for doing that.
The recommended method is to use a product. When in a product, it can upgrade the firmware shortly after connecting to the cloud. This happens within the first 8 seconds or so after connecting. Your firmware should also delay sleep if an upgrade is in progress. This example shows how to do it.
However you need to do that before you deploy the device. There’s no way to wake a device in normal sleep mode remotely since the cellular modem is turned off to save power. It is possible to wake a device over WAN when using cellular standby mode, but this mode generally uses too much power except for remote devices that also have external power, such a large solar panel.