CyanogenMod install failed on Samsung Galaxy S II, phone now shows boot screen and then a black screen I was trying to install CyanogenMod on my un-rooted  Samsung Galaxy S II using this installer. 


I installed the app on the phone and the PC; 
downloaded the data for the program; 
plugged the phone and it started downloading;


I followed the instructions thoroughly and the phone restarted and started installing the ROM. First, it showed the "Downloading" with the green Android then showed the blue CyanogenMod man for a long while, then the app on the PC said it failed and I should try to restart my PC or disable the antivirus (already did).

So I restarted my PC. Now it said "If you tried all these things, it's safe to restart the phone". So I turned off the phone and now when I try to turn it on it shows the splash "Samsung Galaxy" then shows a black screen (not off).

I tried booting in Download mode ("Vol. Down" + "Home" + "Power" button) but the result is the same as turning it on.

Resuming the install process fails every time.

How can I revert back to the stock Android or continue the installation? 



System info (before the attempt):


Model number: GT-I9100P
OS : Android 2.3.6
Baseband version : I9100P
Kernel version 2.6.53.7-I9100PXXKL1-CL761356 root@DELL131 #2
Note: Keep in mind, Samsung Galaxy S2 has infamous Superbrick bug. Every flash can result in permanent brick (only board changing or maybe JTAG unit can recover device). You can learn more about it here.
Note2 : Last resort to enter Download mode is to get USB JIG. There is plenty of this on Internet and it's very cheap. Also there is tutorials on Internet to make it yourself, if you can't get it shipped in your country.

You can try to:

return to stock ROM
install custom recovery, wipe data/cache/dalvik/system partition and reflash custom ROM

Steps for returning to stock ROM:

Download ODIN.

Download Stock ROM from Sammobile site.

You will probably get zip file with one dll and one tar.md5 file. You need to unpack only tar.md5 as it is the file you need to flash.

Put your device in download mode - Pull off battery, insert it again, push &quot;Vol Down&quot; + &quot;Home&quot; + &quot;Power&quot; button.
Now connect it into PC using USB cable (check if you have install Samsung USB driver, search on Google for it)

Only check auto-reboot and F. Reset time! Repartition must stay unchecked.

Put unpacked tar.md5 in PDA section (if you downloaded Odin v3.07, can be different on other versions).

Click Start. Do not unplug your phone or it will result in a brick.

Phone will reboot and if everything went OK it will finally boot.


Steps for recovery solution:

Download ODIN.
Search XDA-Developers for CWM flashable file (I will try to post it in a comment, I cant post links anymore - reputation) and download it.
Search for Recovery-flashable file of CM that you need - usually just zip file. You will need to put it on External SD-card and insert that SD-card in the phone.
Put mobile in download mode, make sure you have Samsung USB drivers, and that in ODIN you have only checked Auto-Reboot and F. Reset Time. (Also connect your phone into PC).
Put recovery tar.md5 in PDA section and click Start.
Now pull off battery, insert it again and press &quot;Vol Up&quot; + &quot;Home&quot; + &quot;Power&quot;.
Wipe /data,/system,/dalvik,/cache.
Go to flash and select zip file that you downloaded from SD-card.
Flash it.
Reboot device, and check whether it works.


Note3 : Be aware that following anything involves flashing can result in permanent brick of the device. Maybe it is even smarter to take in to service so they can better fix it.
Also, I or others (including this website) shall not be held responsible for any damage that may be caused to your device by using the aforesaid instructions.