[HTC Flyer, EVO View 4G] globatron:
If you followed the easy install guide then you want to follow this this post

Please see THIS THREAD before doing this procedure, you might be able to avoid using the HTC unlock.

WARNING: This procedure applies to flyers (not View) only and should be used only if you get the following message when trying to downgrade:

"Main Version is older! Update Fail! Press <POWER> to reboot"

If you upgraded to HoneyComb using the Official OTA perform these steps, otherwise skip to section "Downgrade" below

Perform a HTC unlock using the HTC unlock website

Download this recovery download MD5: bb366b025dcc454ffe8b21b8bf0c72d0

Download superuser from here

Copy the su zip file to the root of your external SD card.

Boot the flyer to fastboot mode

Flash recover

fastboot flash recovery recovery.img

Reboot to recovery and install the su zip file.

Reboot to android

Proceed with the downgradre procedure below.

Downgrade

First download the RUU for your device from this thread.

If there is no RUU for your region/operator, download one of the unbranded ones and create a goldcard​

If you don't know which RUU to use see post #2.

Download misc_version_universal.zip and extract the misc_version file from it.

If you don't have adb and fastboot on your PC

Get fastboot and adb tool for windows here

Get Fastboot and adb for linux here

check the version number for your RUU

In my example I am using this RUU: RUU_Flyer_HTC_WWE_2.00.405.3_R_Radio_20.3501.30.08 9BU_3809.05.04.10_M_release_194964_signed.exe

The version is the part highlighted in red.

Boot your flyer up to android if it's not already on, with usb debugging enabled and connect it to the PC.

Run the following command:

adb push misc_version /data/local/misc_version

Run the following commands:

adb shell
$ su (make sure your screen is unlocked so you see a toaster notification if it appears)
# chmod 777 /data/local/misc_version
# /data/local/misc_version -s [COLOR="Red"]2.00.405.3[/COLOR]

Note that the number in RED is the version number retrieved in step 4.

You will see a message about backing up and writing misc partition

Reboot to fastboot:

adb reboot bootloader

[*]Relock the bootloader:

fastboot oem lock

Run your RUU

If you have correctly completed the process you will no longer get the "Main Version is older! Update Fail! Press <POWER> to reboot" message and you will be able to downgrade to GingerBread.

Note: By choosing an appropriate value for the version it is also possible to return to a specific operator ROM if you have previously upgraded with a goldcard and you have a suitable original RUU. If using the procedure for a downgrade within gingerbread you must first root the flyer and skip step 8. For example you can downgrade from a WWE RUU to an O2 RUU.

Special Thanks

Alastor_ru for testing this procedure for me.

Grkdotnot and RMarkland for testing the procedures for BestBuy Flyers

Donations

lpasq, RMarkland - Many thanks for the contributions; your donations will be used to facilitate the search for full S-OFF.

For support please join the IRC channel #flyer-downgrade on freenode. If you don't have an IRC client you can use the following link #flyer-downgrade