Hello everybody!

I was given a used Asus T200TA from a friend and im trying to fix it up for my kids to use as media player/streamer.

But it seems somewhat unstable, it shuts down randomly and unexpectedly, with no warning or error logs.
The device usually works just fine for about 10-90 minutes, benchmark program runs just fine with no hints of thermal issue, but in the middle of doing "nothing/anything", the device just suddenly powers down, like the battery was suddenly disconnected.
After it shuts down it starts just fine with no warning or error and works just fine untill the next time it shuts down unexpectedly.

The issue can occur regardless of connected perifirals (with AND without the keyboard dock, with AND without the power adapter connected) and seems unrelated to software.
The device was running Windows 8.1 when i got it and the error made me update bios, drivers and system to the latest versions, so im now running on Windows 10 (32bit), freshly downloaded from Microsoft.

I did a fresh install (deleted all the partitions on the internal drive in the Windows Installer) to windows 10 (from USB) and the error is still there.

I did notice a exclamation mark on a "Intel(TM) Trusted Execution Engine Interface" in device manager in Win8.1 that wouldnt go away even with the fresh win10 install and subsequent updated driver install.
When i open the properties for the trusted engine, the device status (in the first tab; general) says "This device cannot start (Code 10) STAUS_DEVICE_POWER_FAILURE" and the 4th tab (events?) says that "Device has not started (TXEI)" in the short description, and i get the following in the "info"-pane at the bottom of that tab:
"Device PCI\VEN_8086&DEV_0F18&SUBSYS_173D1043&REV_0D\3&11583659&0&D0 had a problem starting"
Driver Name: oem30.inf
Class GUID:{4d36e97d-e325-11ce-bfc1-08002be-10318}
Lower Filters:
Upper Filters:
Problem: 0xA
Problem Status: 0xC000009E
(END Information)

I did disable fast boot and hibernation/sleep with no change in regard to the issue, ive installed (some of) the drivers found on Asus support page for my device and OS, like SOC-drivers, TXIE and touch drivers, but this doesnt seem to affect the issue at all..

The battery seems just fine, ive been running it without the power adaptor for about 4 hours today and currently have about 40% battery charge left and as i said, the problem occurs with AND without the power cord connected.

The only apps ive installed are 7zip and firefox, and eventually the "PerformanceTest" benchmarking app, while the issue occured before AND after i installed the apps.

So does anyone have any ideas or hints for me?
Im unwilling to give up on this device since i cant afford to buy another one and i really want my own computer back (witch my kids are using to watch netflix and so on)..

As a separate question;
Is it possible to upgrade RAM on this device?
Does anyone have a service manual or link to a teardown/take-apart-guide?

..my search engine doesnt return anything useful, even tho ive spent hours trying to find the answers myself..

Thank you in advance for your time and effort!