Hi en10,
A couple of things to mention here. The RUU you are running is for the Virgin Mobile Variant of the Evo 3d but more importantly, you will need s-off before you can downgrade your hboot version. Also, you'll want 1.50 as 1.49 is a GSM bootloader version.
You will want to use the Juopunutbear (wire trick) method for s-off. All the instructions and downloads for that are here:
Unlimited.IO
S-off will be required before you can downgrade your bootloader version.
They tell you to be on the stock RUU. You might be fine on your current setup, but if you want to play it safe, here are the steps for you to successfully complete an RUU for your setup.
1.) Flash
THIS FILE via your custom recovery. If you don't have a custom recovery installed, you will need to unlock your bootloader again. Place the file from the first link on the sd card. Then place
this in your fastboot directory on your PC. Use the command:
fastboot boot recovery.img
Once in recovery, install the zip file that you placed on your sd card.
2.) Place the phone into fastboot USB mode from the bootloader screen. Run
this RUU on your pc. When it asks you to plug in the phone, go ahead. Go through all the promts/instructions provided by the RUU and you'll be fully stock RUU in about 5 or 10 minutes.
To proceed with s-off, follow the instructions provided by team unlimited linked above.
Here is a helpful video about the wire trick that will show you the proper timing to get it right.
Once you have s-off:
1.) Download the latest superSU
HERE. Place that on the sd card in your phone.
2.) Place
THIS recovery.img in your fastboot directory on the pc. Issue these two commands in order: First -
fastboot flash recovery recovery.img
Second -
fastboot boot recovery.img
3.) Root the phone. Once the recovery boots after issuing the last command. Install the superSU file on your sd card.
4.) Download the rom of your choice. I assume you wanted to bootloader downgrade to use a jellybean rom? Place the rom you want to use on the sd card.
5.) Download this hboot version:
https://app.box.com/s/9mnmwboybvx6jz6jq6fs
Place the file on the
ROOT of your sd card (can't be in any folders).
6.) Download this app:
https://play.google.com/store/apps/details?id=com.siriusapplications.quickboot&hl=en
Run it and select recovery. Grant it super user access when it asks.
7.) From recovery, install the rom.zip you chose to use.
8.) Once the rom is successfully flashed, boot into the bootloader (from recovery is easiest - without booting back into the system first).
9.) The bootloader should detect the hboot file that you placed on the root of the sd card. When asked to update, say
yes by hitting
volume up. When it's all finished, hit
power button to reboot.
Important! After booting up, immediately rename or delete the file (PG86IMG.zip) from the root of your sd card.
That should be everything. This should get you s-off, on hboot 1.50 and a rom of your choice!! Good luck and let me know if you get stuck.