Here is the process to revert back to the AT&T or HTC ROM and bootloader after flashing a non-OEM ROM on your device.
Note: If you had to use jockyw2001's "White Screen" fix in order to install HardSPL you will need to use it to revert back... below where the steps reference SSPL-KAIS.exe replace them with jockyw2001's JumpSPL1.56-SSPL.exe. You can obtain the files from his thread.
ok... Assuming you're starting with a Kaiser/Tilt with HardSPL and the ROM that didn't come installed on it:
1. Reflash the OEM ROM
2. Extract the OEM ROM with NBHextract.exe
3. create a new NBH using htcrt using only the 01_SPL.nb
4. Put your NBH file containing only the SPL into an empty directory on your PC
5. Copy KaiserCustomRUU.exe to that folder
6. Copy the SSPL-KAIS.exe to your phone (if you had to use the White Screen fix you'll need jwocky2001's JumpSPL1.56-KAIS.exe)
7. Run SSPL-KAIS.exe from your phone (or JumpSPL1.56-KAIS.exe, depending on your situation)
8. Flash your "custom" NBH containing only the SPL.nb by running KaiserCustomRUU.exe
9. After it's finished verify your SPL by holding down power and camera buttons while doing a soft reset.
10. Send your phone back to HTC or ATT
pretty sure I've covered it all... Let me know your results. I've done this successfully following the steps above.
Idiot's Guide to Restoring your phone to OEM Status
1. Get the original ROM for your device (HTC or ATT)
2. Flash the OEM ROM to your device (this will restore your OS but not the bootloader, we'll get to that below)
3. Copy the ROM to a temp folder and extract it, I use WinRAR, just right click on it and select "Extract to Here"
4. After extracting the ROM you should have a several files here, one called RUU_signed.nbh is the one we're looking for. Copy this file to another empty temp directory.
5. Download NBHExtract and follow the instructions in the link to extract the NB files from the ROM (essentially just copy nbhextract.exe to the temp folder where the nbh file is and run it from a command line - like so C:\temp\kitchen\>nbhextract.exe RUU_signed.nbh
6. You should now have several .nb files in that directory, the one we're interested in is the 01_SPL.nb.
7. Now you have to create an NBH file with just the SPL, to do that download htcrt (HTC Rom Tool).
8. Run the tool and under the ROM Builder tab select Kaiser, the rest on the left side doesn't matter right now. On the right side of this window click the "..." next to SPL and select the 01_SPL.nb you extracted from the OEM ROM. This should be the only thing added under Firmware Contents. Click Build ROM.
9. You should now have a NBH file that is relatively small (about 258K), copy this NBH file to a new empty directory
10. Download pof's KaiserCustomRUU.exe and put this in the same directory used in step 9. Don't run this yet.
11. Download pof's SSPL-KAIS.exe and copy it to your phone
12. Run SSPL.KAIS.exe from your phone (make sure you do this on your actual device and not your PC)
13. When you have the bootloader screen on your phone run KaiserCustomRUU.exe from the folder used in step 10.
14. After it's finished verify your SPL by holding down power and camera buttons while doing a soft reset.
15. Send your device back for warranty repair or replacement.
For ATT users ONLY
Steps 3-10 (Idiot's Guide) just made easier... download this file, unrar ... resume at step 11 if you download and use this file (you only need one of these, pick the one that matches the stock ROM you installed)
Original ATT SPL - http://rapidshare.com/files/92272343/ATT_SPL.rar
Updated ATT SPL - http://rapidshare.com/files/92269531/New_ATT_SPL.zip Feb 14, 2008
For HTC users ONLY
Steps 3-10 (Idiot's Guide) just made easier... download this file, unrar ... resume at step 11 if you download and use this file
For users that were originally running the 1.81 SPL credit: rock4mayo
For users that were running other Shipped ROMs
See jcespi2005's Reconstructed ROMs thread and/or the Shipped ROMs wiki
FYI... this is all at your own risk, I don't guarantee my files are working, though the ATT one worked for me, your best bet is to make your own. I also take no responsibility for any damage you do to your phone following these steps or using these tools... Best of luck to you.