[EVO 4G Q&A, Help & Troubleshooting] steve19137:
so, basically everything that you have done has been done before. many people seem to think that they are unique and unconventional by trying all the simple things first. no worries, i tried what you did too minus singing with a kitchen. i must say, the kitchen piece is another step that i didnt think necessary.

anyhow, this information that ill share with you will hopefully help you (and anyone else) to understand exactly why we cant do anything ourselves. when the bootloader finds the package in the sdcard, it does two things. first, it loads it into the internal memory. we know that because people have actually taken the battery out of the phone while having it plugged on, and thought they could trick the bootloader into flashing an older package after the checks on the newer packages went through (by switching out sdcards with different packages). results showed that it still flashed the new package because it copied it into the internal memory temporarily.

second, once its done coping the package over, it compare the signatures against two keys, a public one and a private one. the private one is obviously the most helpful to us, but not attainable. each official package has both keys in them, and the match with the bootloader perfectly. whenever you do ANYTHING to the package, it either deletes the keys or changes them. in your case, you effectively changed them because you signed it with another tool. i never thought about signing them when i was tinkering with the various files, and so my packages simply didnt have a key.

so, heres how it is: teamwin is the group of people that you want to be watching. they will most likely release the root based of this single tweet here: http://twitter.com/#!/agrabren/status/100043987599101952

that guy has done some pretty big things for WiMax in AOSP roms, and i think was involved in the evo 3d root also. im not entirely sure, i cant remember right now. but he knows what hes doing. teamwin is made up of about a dozen people who are essentially engineers by trade. ive heard that they (or someone else) have found a potential exploit in the og evo gingerbread kernel. ive also read that many devs has been able to successfully s-off the 2.16 hboot, but the procedure just about bricked their phones, so they wont be releasing those particular tools.

either way, the root is coming. these guys make just as many mistakes as we do, and one of them likely accepted the OTA and locked their device, and are just as desperate as we are for a way out.

but at this moment in time, we all have two options: become the worlds fast learning brain and learn multiple code languages and root the evo by next weekend, or just wait patiently. i have chosen to wait patiently. i hope many others can do that too. and i hope this was helpful for you.

EDIT: just saw your post about testing with the EXE RUU, and thats even harder to get past than the bootloader. that has checks of its own, besides the ones that the bootloader runs. but, if you want to play with the black HTC screen some more, make these commands. boot into the bootlader, enter into fastboot, and in ADB enter "fastboot oem rebootRUU". that will take you to that black screen, and you can try and push things from there and such, but you wont get anything because its still the bootloader making checks.