Convert ISR1100-4GLTENA from IOS XE to Viptela OS

[maxnpj]

So we received ISR1100-4GLTENA units with IOS XE on them. Right now we would prefer the Viptela O/S. Can I convert this *back* to Viptela O/S? I've come across several documents detailed changing the O/S *from* Viptela OS *to* IOS XE , but I haven't found anything dtaling how to go the other way. 

It is currently running 17.4.1a if that matters. 

Thanks

[BryanHefner2568]

https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/sdwan-xe-gs-book/install-upgrade-17-2-later.html#mode-discovery-and-mode-change-with-bootstrap-files