Failed Exchange 2013 setup - catch 22 situation

Dear all,

Trying to install a new Exchange 2013 server here.

Launched the GUI setup, went through the various pre-requisites and launched into the meat of the matter. It seemed to work fine until I got  failure in the HubTransportRole.

Now I have an incomplete install.  Setup will not run in "normal" mode, instructing me to run in /m:RecoverServer mode. That generates two new errors:

[06.26.2014 07:39:36.0559] [1] [REQUIRED] The language pack bundle could not be found or is corrupt.                                 

No idea where this is coming from - it's the very same server that passed pre-requisite checks a few minutes ago...

[06.26.2014 07:39:36.0569] [1] [REQUIRED] A Setup failure previously occurred while installing the HubTransportRole role. Either run Setup again for just this role, or remove the role using Control Panel.

Well that's what I am trying to recover from... I can't run setup to remove this role as it instructs me to use RecoverServer, yet RecoverServer instructs me to use normal setup... A bit of a catch22.

This is Exchange 2013sp1 on Server 2012R2.

Any suggestion / pointer most welcome