[EVO 4G Android Development] haxt:
I was one of the people that did the initial backup methods (telling you how to backup your certificate and rsa keys) or using cat which doesn't actually backup your wimax.img properly. After hours of playing around in a hex editor I finally got my 4g working again, and i'll explain how :)

****EDIT****

I added a hex converter you can use for your rsa key if you are too lazy to find one on google. I say to use hex instead of text replace because it's safer in regards to \n's

I was too lazy to make a gui for it but its haxt.net/evohex.php?rsa=yourrsa&cert=yourcert [obviously replace it with your 2 values]

Also, don't try to flash this image without editing it. The rsa key is invalid until you put your valid key in!

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Note - this won't work for anybody who actually has no idea what their RSA keys/certificate is.

So there are a few things you need first.

1. Your phones wimax mac address (take out your battery and look at the sticker)

2. Your RSA private key

3. Your Certificate

4. The wimax image file template I attached here in the zip

To simplify, use XVI32 freeware hex editor. If you search "BEGIN" you will see begin rsa key and begin certificate. You need to copy these values for later use.

Download the template file and open it in the hex editor.

Our template's mac is 00:18:41:81:8B:5C

Our templates Certificate is :

http://pastebin.com/vEnKFtS8

Our templates RSA Certificate is :

http://pastebin.com/gJbrh3ii

Convert both of these strings to hexidecimal and write them down! (it will look like a bunch of 4D 49 49 44 6B 44 43 43 41 6E 69 67 41 77 49 42 41 67 49 51 5A 4F 75 35 44 5A 4C 55 44 76 44 57 4B 57 2F 36 6D 48 66 4C 4F 54 type stuff)

If you don't know what your rsa key or certificate is, open it up in a unix friendly text editor(on windows i recommend notepad++). Search case sensitive for BEGIN. You will see the begin rsa key and begin certificate. Copy all of the text in between with no spaces or newlines! Now convert these both to hex and write them down.

Hit search -> replace on xvi32, click hex search and paste your converted hex for the templates RSA key.. and then replace with the hex value of YOUR rsa key. Do the same thing for the certificate as well.

The length of our templates rsa key might be different than yours, and your ending file size MUST be the same as your starting file size(the template is 12,582,912 bytes). There are a bunch of null characters in the template after --END KEY--- you might need to add or remove some to correct this! Just click on one and press the delete key if you have to :P

Now the only thing you have to do is fix your mac. In your new wimax partition file, text search for 00:18:41:81 to Replace that mac with your mac but subtract 1 from the last digit(if your mac was 00:23:76:EC:21:D4 put 00:23:76:EC:21:D3).

Replace the first 2 of the 3 instances with your mac -- minus 1. (If it ends on a letter, B would become A, C would become B, etc.

The last instance of your mac, put the actual mac address with nothing subtracted as it appears on the sticker under your battery.

Once you have saved the file.. name it something like wimax_fixed_resized.img and copy it to your sdcard.

Boot to fastboot and run "fastboot erase wimax"

Reboot to your recovery and adb shell in.

type "mount /sdcard" so you can run flash_image properly.

Run flash_image wimax /sdcard/wimax_fixed_resized.img

(or whatever you named it)

Profit!