[Sony Xperia S, Acro S, Ion] Mirhawk:
Ah no biggies!:)

You need to have unlocked bootloader

for this.

You can unlock bootloader here. But first backup DRM keys using procedure here.

This Guide is for Kitkat ROM's.​

Got everything now. Follow the following steps, You will have the ROM in Your phone by it:

1) Copy both the ROM.zip and gapps.zip to Your phone.

1) This step is on PC.. Download this boot.img. This is required as the boot.img of some Kitkat ROM's don't have TWRP built in or have incompatible recovery. Rename it to boot.img

3) Then copy it to "C:\Flashtool\x10flasher_lib" or wherever You installed the flashtool. We need to copy this to there since we need to use 'adb.exe' and 'fastboot.exe' from here.

4) Open command prompt on the same path as above.

5) Switch off Your phone. Then connect the cable to PC but not to phone. Press volume up button on Your phone and while pressing it, connect the cable to phone. Blue LED will lit up. If there is no blue LED, do this step again.

6) Then use these commands in command prompt to flash the boot.img to the phone:

fastboot flash boot boot.img

The boot.img is used to just get the TWRP to the phone to flash the ROM.

7) Now Your phone won't boot normally if You try to do that. What You need to do is as soon as the device powers up, try entering recovery. Since we flashed the boot.img, it will boot into recovery.

8) Then format system, data, and cache. This will delete all Your apps and their data. It won't delete Your sdcard data. Be careful, don't format sdcard by mistake!

9) Now flash the ROM.zip from recovery.

10) Format cache and dalvik cache only.

11) Flash gapps from recovery.

12) Reboot! Done!

The first boot and reboot are a bit long. During reboot, the phone will seem to be stuck at the Sony logo, but it is just processing, so no need to worry.

In case You don't have TWRP after flashing the ROM, You can follow the procedure from here to flash the recovery.

Kitkat instructions end here.

Lollipop ROM:​

Link to Android Lollipop (5.0) gapps : Link.

For flashing the AOSP ROM's:

1) This step is on PC.. Download this boot.img. This is required as the boot.img from AOSP Lollipop ROM's don't have inbuilt recovery. Download the the root binaries from here if You are using Pure AOSP ROM by billchen1977 only.

2) Copy the ROM.zip, gapps.zip and SuperSU.zip to Your phone.

3) Then copy boot.img to "C:\Flashtool\x10flasher_lib" or wherever You installed the flashtool. We need to copy this to there since we need to use 'adb.exe' and 'fastboot.exe' from here.

4) Open command prompt on the same path as above.

5) Switch off Your phone. Then connect the cable to PC but not to phone. Press volume up button on Your phone and while pressing it, connect the cable to phone. Blue LED will lit up. If there is no blue LED, do this step again.

6) Then use these commands in command prompt to flash the boot.img to the phone:

fastboot flash boot boot.img

The boot.img is used to just get the TWRP to the phone to flash the ROM.

7) Now Your phone won't boot normally if You try to do that. What You need to do is as soon as the device powers up, try entering recovery by pressing volume up button when the LED turn blue. Since we flashed the boot.img, it will boot into recovery.

8) Then format system, data, and cache.. This will delete all Your apps and their data. It won't delete Your sdcard data. Be careful, don't format sdcard by mistake!

9) Now flash the ROM.zip from recovery.

10) Format cache and dalvik cache only.

11) Flash gapps from recovery.

12) Do this step only for billchen1977's Pure AOSP ROM! Flash the SUperSU downloaded in the first instruction. If You are flashing nAOSP by mickybart, don't follow this step, skip to next step.

13) Reboot!

14) After flashing the Lollipop ROM, You loose Your recovery, You can get it back by following the procedure here.

15) After flashing a Lollipop ROM, the first boot displays only boot animation for 10-15 minutes. This doesn't mean Your phone is bricked, it is just initializing the apps. During second boot, it will seem to be stuck at "Sony" logo for 5 minutes. This is also normal.

Suppose You are not able to recover at some point and can't wait for next reply, You can flash a stock firmware using flashtool.

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