Still Trying To Root

You say trying to root but it sounds like you are trying to install a custom recovery.

Go into bootloader (assuming you unlocked it), highlight fastboot and press power. Plug phone to pc. Should now say fastboot-usb on phone screen.

Then the command is fastboot flash recovery nameoffile.img

 

I typed in "fastboot -help" in a Linux terminal, and fastboot boot recovery is not a valid command.

Try fastboot reboot-bootloader then go down to recovery with volume keys and highlight recovery, then hit the power button.

 

Or assuming that you have a current version of your recovery in the same directory as fastboot you can use this command:

fastboot boot file_name_of_your_recovery.img

The command won't work if you use "recovery.img" as the file name and that's not a valid recovery file.

Since the recovery program contains a kernel that is bootable I use that after flashing a bootloader through fastboot to go directly to recovery to clear cache+dalvik instead having to start it from the new bootloader. S-ON users can use the same command to enable flashing the boot partition from recovery.

Either method will work.

ramjet73

 

You don't want RA recovery for the Evo 4G (supersonic) and I have no idea what the recovery.img file is. If you know that is a good copy of CWM, 4EXT or TWRP for the Evo 3D/V it should be bootable using that command, otherwise you are probably better off starting recovery using the bootloader method.

If you use the command, make sure you specify the complete file name ("recovery.img" and not "recovery"). The file extension may not show if you haven't selected the option in Windows explorer.

ramjet73

 

Or you could download goo manager and under setting install recovery! Assuming that your bootloader is unlocked!
Edit: https://play.google.com/store/apps/details?id=com.s0up.goomanager
In setting select install open recovery scripts! Then boot into recovery, to confire your new recovery

 

If you are using Windows, you need to install htc drivers.

 

Just s-off that bitch. Far less trouble. Then you don't need the update. I mean wow. You are going thru some crazy stuff just to get a updated phone. I once was super intimidated with s-off. I actually thought the process was kind of barbaric. But now I have done it over a dozen times. And root and s-off can be achieved in less than 1 hr

 

I usually try not to direct people away from the guides on this site since the users here are familiar with them but I have a guide on XDA that I tried to simplify as much as possible.

ramjet73