[Source] - xda-developers
What is the SPL? (Second Program Loader)
The SPL is mainly a bootloader which allows a ROM to be flashed onto your device. As has been uncovered recently (or known to the more astute longer) the SPL does more than just load and boot the ROM it sets various flags which can control the operation of the OS on the device. It also controls some operations between the OS and the device's hardware. SPLs come paired with shipped (or leaked) official ROMs and are meant to match the ROMs operation. Therefore, with each new ROM release there is likely to be a new SPL.
What types of SPLs are there?
Basically there are two main types of SPLs. Hard and Soft.
A Hard SPL is one that is permanently flashed in your device memory and will boot up every time your device boots. To get into your SPL or Bootloader on the Kaiser/Tilt you want to hold down the camera button (all the way) and then soft-reset the phone (or turn it on if it was off). You will then see a tri-color screen known as the Bootloader (a.k.a. the SPL). The SPL that is shipped with your device, or upgraded from an official ROM is a Hard SPL. In short, if it is loaded into your device's firmware, and survives a hard-reset it is considered Hard.
A Soft SPL is a stand alone .exe that is run on your device from within the OS. It basically changes your OS from running Windows, to initializing the boot loader. A Soft SPL is only loaded into RAM temporarily and will not survive a hard-reset.
Instructions to flash Hard-SPL:
it's recommended you run the basic package, and don't flash the other attachment (MFG SPL - it is only for hackers).
0a) make sure you have .NET framework installed on your PC! if not, get it from [Here]
0b) if you have vista, WMDC update is recommended. [Link]
1) download Hard-SPL package from attachment, extract to an empty folder.
2) it is recommended you download only the [X1_HardSPL_v1.zip] unless you want to tinker with MFG SPL (MFG SPL 0.52 is a separate attachment).
3) you must Have Phone Synced with PC in Windows Mobile!
4) run X1_HardSPL.exe. (if you want to flash MFG SPL: at this point replace the extracted RUU_Signed.nbh with the MFG version of RUU_Signed.nbh)
5) follow steps in the RUU, and check on the device for prompts after PC shows loading bar.
6) it should go to tricolour screen now and say 0.52.OliNex.MFG (this is SSPL!).
7) Hard-SPL flashes, device automatically reboots, job done.
8 ) to confirm you got it installed, go into bootloader mode (tricolour screen!) and verify the screen shows 0.72.OliNex (or 0.52.OliNex MFG).
NOTE: you will not see the SPL version during normal boot, that is the OS version, not SPL!
to enter bootloader mode to see version: with the device turned OFF, press and hold the volume down button along with the power button, then release the power button, and finally release volume down button when bootloader tricolour screen appears.
NOTE 2: anyone having problems with the device entering SSPL automatically(your device doesn't go to tricolour screen), please copy Xperia-SSPL-Manual.exe from the Xperia-SSPL-Manual.zip attachment to the device and run it. then once the screen is in SSPL (tricolour screen saying 0.52.OliNex), run RUU on the PC (i.e. the rest of the hardspl package) manually.
NOTE 3: this is unsigned Hard-SPL. also, this has overwrite protection, if someone needs to revert to stock SPL for warranty reasons, a stock SPL downgrade package is also available here - scroll down!
NOTE 4: do not use this RUU to flash anything else! this is only intended for flashing the Hard-SPL. use Xperia CustomRUU to flash other ROM images. for example this version: [Link]
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IMPORTANT: extra Xperia-specific notes: the prerelease roms out there in the X1 ROMs thread are not going to flash on retail devices because the radios they include are only flashable on prerelease devices ("Security unlocked" message in SPL can be seen on these). so what you need to do is repack the NBH without the radio - this will only work with Hard-SPL though, as repacking breaks the HTC sign on the NBH file.
I had a tester upload a repackaged UK image, which will flash fine. you can find it in the x1 roms thread. =)
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TROUBLESHOOTING TIPS:
- read the instructions.
- read the instructions.
- read the instructions.
- if you get connection error in RUU after the device goes to tricolour screen, then try a different USB port, also do not use USB hub, you can also try rebooting your PC, and can try using another PC. read the thread for even more tips that I don't remember now. also you can try unticking advanced network functionality in start menu / settings / connections / usbtopc applet.
- if hardspl EXE won't run, and you are on vista, try to right click it and use "run as Administrator" option
- if SSPL-Manual.exe or enterbootloader.exe fails to run (says missing component or similar), try a hard reset of the device.
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Extra how to: how to restore Stock SPL for warranty reasons.
step by step:
- this is ONLY for warranty reasons. i.e. the device needs repair and you have to send it to htc to get it serviced. if you plan to restore hardspl then don't even bother flashing this stock package, unless you are some kind of hacker/dev
- IMPORTANT: be sure to first restore stock OS, and stock radio. stock SPL is always to be done last!!
- now the steps
1. download the stock spl package from this post.
2. download X1_HardSPL_v1 too, from this post.
3. run the hardspl package, but do not press Next button i.e do not go ahead with flash yet.
4. at this point, take the extracted stock SPL, a RUU_Signed.NBH file, and overwrite the other RUU_Signed.NBH in hardspl package.
5. go on with the RUU (or if needed, run SSPL-Manual.exe manually, then run RUU when it goes to tricolour screen with 0.52.OliNex version), it goes to 100%, reboots, done.
+1. to verify, enter bootloader (see description above in this post), and check version number on tricolour screen. it should say 0.72.0000
