Generally tech support from companies wouldnt involve you trying to fix it on your own with adb/fastboot/nvflash since unless you knew what you were doing there's a real chance you'd make things worse, though given if you knew enough to try those hopefully you'd know enough to at least make things worse.
Not critizising, just trying to give perspective.
I've done a little studying on the s7, but I cant offer much yet. I once managed to somehow brick my loaner s7 and we looked at the adb log and it had a slew of 'nand is in read only mode' stuff.
I reflashed the stock rec and fac resetted and that seemed to fix it, but I kinda doubt it was a true read-only event since we easily fixed it.
Lost all his data though, but he didnt have much on it since i was using it to dev and there's a very real risk i'd brick it and have to rebuild the partitions anyway.
It's a really long shot in the dark, but have you tried fac resetting with a stock rec installed? Though I cant tell if flashing a new rec would even stick at all.
The Streak series have no protection at all, even the s10 is unlocked, apparently it's relatively easy to make locked devices by using the Secure Boot Key command, but that's at the designing stage for a device, you wouldnt go and slap it onto unprotected devices, it's all or nothing.
One final note, for some reason both the s7/10 start at partition #2, there's simply nothing before that as the sector location of partition 2 starts at 0, so there's nothing hidden before it. If there was it's silently converting sector numbers on the fly so it THINKS partition 2 = start from sector 0, which is pretty crazy sounding.
Mabye all tegra2's start at partition 2.