how do isp's block configs?

[Romerro]

If you were the ISP there are any number of ways to kill a config like that, perhaps start enforcing expiry dates, co-signing, or dynamic generation.

Here's an idea. Use a provisioned modem, running Haxorware or other to grab and download its current config file to a PC. Upload that same config file to that same modem to save it to the list of configs available to push, like we used to could do pre/security that disabled that Haxorware push; now that you have it uploaded and saved as an available config to choose, select this config file, which is the same as the one that your modem is currently using, then select BPI+Bypass, save and restart. See if that answers any questions for you.. Should your modem come back online or should it continue into a boot-loop.. (Some statements are redundant for clarity).