Nandroid will not always save you
TWRP will not always save you
If you can, HAVE your RUU (Rom update utility) for your phone. IT will save you – unless you have a hardware problem.
If you have an HTC – please have S-OFF before you do anything, because S-ON will not save you.
USB Debugging cannot be turned on once the phone is screwed up. (Turn USB Debugging on before doing anything)
Cautious when flashing boot.img – make sure you have a stock boot.img to go back to. I recommend for HTC devices doing S-OFF so you don’t have to flash the boot.img separately.
ABC’s of Android
What is root, s-off, unlocked boot loader?
Another web site explaining root etc…
Root and S-OFF.
or…. pay someone to do this for you because it’s painful.
The RUU (ROM update utility ) allows you to go back to stock on your HTC device. Note that you must lock the boot loader again if it is unlocked when running the RUU. You can run any RUU that is equal to your ROM or newer.
How to run an RUU.
HTC ONE S last RUU (at bottom – download)
Sometimes you get stuck in a boot loop (HTC logo with red text anyone?) and need to boot up again with the original boot image. Here’s how to get the boot.img for the original ROM. Get to fastboot mode over usb (HTC) and then fastboot flash boot boot.img (note: not needed if you have S-OFF)
How to extract boot.img from RUU
Apparently HBOOT is stored in the firmware.zip file with is in the RUU. So if you want to downgrade HBOOT (from 2.16 to 2.15 etc..) flash the firmware.zip with S-OFF.
Get adb and fastboot easily for OS X. (After installing you should restart and BTW quit HTC Sync Manager if it’s running).
To check a downloaded file – download the file, then open terminal. Type md5 and then drag the file onto terminal to insert the path. Then press enter. Compare the checksum to what you see on the download page.
ADB sideload with TWRP – caught in a boot loop with HTC device (HTC screen with red text)? This link could certainly help you out.
Accidentally pressed Reset Factory Settings in Bootloader when you have custom recovery? You need to flash the stock recovery back on to the phone and then choose Reset Factory Settings again. Then you can put back TWRP or CWM by flashing the custom recovery back.
Install custom recovery TWRP – this is so that you can install ROMS or backup your system.
Here is CWM custom recovery – another very popular recovery.
superSU to grant your apps super user (i.e. root).
Root, unlock, recovery HTC ONE S
Another thread on unlock, recovery and root.
Possibilities with s-off.
How to extract Kernel from ROM
Build environment with OS X
Another link re: building with OS X and another