[Request] CH341a + Surface Pro 5 - downgrade from 239.871.768 to 235.3261.768

Hi! I broke my SP5 display, so I need to open up this cr… tablet. Now, at this situation I think I should reconsider a full maintenance such as battery replacement… etc and, that includes a UEFI downgrade in order to apply some undervolt (since newer versions prevents us from doing it, and sometimes this tablet looks like it came from Mordor).

I have a CH341A programmer, but I dont understand anything c’: (kinda frustrating but i think theres no material about downgrades too). So in the 1st place, can we downgrade using a programmer?

Current firmware:
https://www.mediafire.com/file/hv7i2scfmtiqjb1/current_SurfaceUEFI_239.871.768.bin/file

Desired firmware:
https://www.mediafire.com/file/g085vz61xdn41t7/SurfaceUEFI_235.3261.768.bin/file

Thanks. c’:

That’s the structure of firmware for a working Surface pro 5

image

That’s what is in your files:

You can see that you have 4 Efi volumes and 1 non- empty padding, all are duplicate in the working firmware and need to be exchanged. In addition it might be useful to delete parts of the NVRAM (EfiSystemNvDataFvGuid).

In addition it might be useful to clean the ME region according to

But this may make you loose your touch.

Please post the complete and unchanged output of MEInfo from this package

CSME System Tools v11
For CSME v11

regarding the touch function.

Hi, lfb6!

Im sorry. The last 3 days were a nonstop. I dealt with a lot of broken glass pieces, sticky glue… and an exploding battery cell (1 of 4 only) :sweat_smile:

log-from-MEinfo.zip (1.3 KB)

The 2 roms I posted before were a generic update image file. I should post an entire dump from my Surface, right? Is there an utility to do that? Or better use the CH341A way?

Thanks!!

Apparently my SP5 motherboard died. I tried to dump the firmware but IC was unresponsive. Now it doesnt turn on so RIP surface i guess :confused:

Thanks for the MEInfo output!

FW Capabilities 0x11111650
Intel(R) Capability Licensing Service - PRESENT/ENABLED
Protect Audio Video Path - PRESENT/ENABLED
Intel(R) Dynamic Application Loader - PRESENT/ENABLED
Intel(R) Precise Touch Technology - PRESENT/ENABLED

The last capability can’t be configured in FIT, it has to be enabled by fpt command wjile the machine still is in manufacturing. That’s why I asked.

Otherwise sad to hear, but you saved a lot ot time bricking it just in the beginning. You might’ve kicked a small / microscopic smd part from the board when working with the clamp or when dismantling. Non responsive chip or reading just FFs is often bad positioning of the clamp.