Well, the environment variables suggest that you could also do it over nfs, which would be considerably more convenient than setting up a tftpboot server.
In any case, it looks like we will very soon be needing an image to actually drop on here. Can you make one from your good PE using BusyBox?
We could probably drop the files via nfs or kermit if you've got an image ready.
It's interesting - they clearly put a fair bit of effort into making it easy for *them* to fix broken edge software, but then failed to make it easy for anyone else to do so. The below variables suggest that they have a recovery SD image which can be used to do maintenance, as well as a tftpboot server and nfs file system set up for copying shit.
If any of the real Edge devs are lurking here in the forums, you could toss us a bone and send us your maintenance image.