No one builds router that cannot be factory reset.
Verizon does. Got one here, ordered off of ebay, Verizon firmware, cannot log in, cannot access router settings via TR-069 head-end, cannot factory reset (does nothing).
If I recall the VZ router firmware settings, that's not too hard to do, if you're a "network wiz":
1) set a different password for admin account, other than what's on the sticker.
2) block the TR-069 port on the firewall.
3) change the "Reset Button Action", to "Do Nothing", or something OTHER than "Factory Reset". (Yes, in all stupidity, VZ lets you do this. Tomato does do.)
If you think that you have SkillZ, and can Factory Reset it, let me know, I'll send it to you. I've tried the Factory Reset instructions in the manual, as well as a so-called 30/30/30 reset. No dice.
Edit: Ok, the offer is off of the table. After posting the above, I decided to give it another go, trying to factory reset this darn VZ G1100 router, and I'm happy to report that I was wrong.
What was really happening, I guess, is that it WAS resetting, but due to me using Firefox Nightly, it was going directly to the Login screen, and NOT accepting the password on the label.
I tried using IE8 (or was it IE11) on this Windows 7 64-bit laptop, and it went to a sort of introductory thing, like "Let's set up this router". Quite a difference the browser makes!
Once set up with IE, I logged off, closed IE, and then I was finally able to Login with Firefox. Weirdness.
Bad firmware coding, to be so dependent on Windows-based browsers? What if I were a Linux user, and didn't have a Windows box with IE handy?
Strangely, though, the replacement router that I got from the same ebay vendor, when I told him I couldn't reset or login to the router he sent, he had another one sent, and that one worked fine with Firefox. Again. Really weird. And I'm glad that I turned out to be wrong. I've got a second G1100 router.