PS Vita / PS TV 3.71 & 3.72 Downgrader to 3.65 Firmware by SKGleba

Following the H-Encore2 PS Vita 3.65-3.71 Jailbreak and Sony's 3.72 OFW Update comes a PS Vita / PS TV 3.71 & 3.72 Downgrader to 3.65 Firmware by SKGleba with a dsll-mdr72.vpk guide below

As always, downgrading is done at your own risk so be sure to follow all documentation closely to avoid the possibility of PlayStation Vita / TV bricking!

This tool will make lv0 load plaintext "ux0:data/update_sm.bin" instead of "os0:sm/update_sm.self".

Usage

1.Download and install the VPK
2.Put decrypted update_sm elf in "ux0:data/update_sm.bin"
3.Run the app, it should say "module loaded"
If it hangs or crashes you will need to reboot by holding the POWER button

Notes

Framework injection reliability: 25%
Framework stability: 90%
Before performing dangerous operations such as downgrading please make sure that the framework is stable (i.e by running the settings and welcome park apps)

And here's the Vita/TV 3.72 downgrade guide from Pastebin.com:

How to downgrade PlayStation Vita and PlayStation TV from firmware 3.71 or 3.72 to firmware 3.65.

1) Required files:

PlayStation Vita firmware 3.65: PSVita OFW 3.65 complete.zip (the "full" pup - 302.20 MB)
PlayStation Vita firmware 3.72: PSVita OFW 3.72 complete.zip (the "full" pup - 302.3 MB)
Latest release of modoru by TheFlow: modoru.vpk
dsll-mdr72.vpk by SKGleba: dsll-mdr72.vpk
Decrypted 3.65 update_sm: update_sm.bin (39 KB)

2) Preparing everything

Install both VPKs via vitashell
Copy the 3.65 PUP to ux0:app/MODORU000/PSP2UPDAT.PUP and the 3.72 PUP to ux0:data/PSP2/UPDATE/PSP2UPDAT.PUP if you have a memory card
Copy the update_sm.bin to ux0:data/update_sm.bin
Power off your device

3) Downgrading

Power on your device
Enable homebrew with h-encore2
Start "decsecldr[LITE]", wait until it says "module loaded" and then press [start] to exit
If your console hangs (longer than 15secs) or crashes - hold the [power] button for 20s and repeat from step 3, this may happen A LOT of times, good luck!
Start "modoru" and follow the instructions displayed on screen
That's it!

4) Troubleshooting

If you get a long "floating bubble" before modoru starts - abort the process and repeat from step 3.
If you encounter a crash during the downgrade process (green screen) - reboot to safemode by holding PS+RT+POWER and select update system firmware->update from vita memory card.