Thanks to everyone who might give me some help.
I have a new quad-core phone with android 4.2.1, that is now useless. It can not boot, it freeze at second bootlogo, before animation.
It is rooted, and i have made some changes to build.prop. It worked fine, but after some time i realized the gallery and camera app was gone.
Then i did following:
Installed updated standard gallery+camera apk found online, both in the same app. from here
Works great, but i wanted to make it a system app, so did that with titanium backup.
After that, the camera app is gone. Gallery app is still working.
So i tried to change it back to user app, again with titanium, but did not stop working. After some time i took out the battery.
Now it freeze before boot animation.
I tried "wipe data/factory reset" and "wipe cache partition", in system recovery but still not booting!
I tried to backup user data from another phone, same model, and restore on this one but says "Error: checksum compare fail".
Do i need to flash a new rom to the phone with my pc? I have not tried this before, and i want to keep stock rom.
I have read this page:
But i can not get it in download mode, with those hotkeys?
If it is to any help, i have acces to other working phones of the same model.