Yesterday I was really decided to return to the tablet. But this morning I flash it with the 1.16 bios shared by Hackerjac ( Thank you very much to him for that ).
After that, Kionix G-Sensor come back and Windows memtest has succeded twice 10 pass without error.
I've noticed this 1.16 bios doesn't include the IT8987E eFlash Update 1.0E present in my tablet at the beginning. Perhaps it can explain a part of my prior troubleshooting ?
I am now convinced that my tablet comes without any rootkit. But I'm thinking it was Chuwi labs testing models sold without any reset, and perhaps even with an unappropriated IT8987E Update who cause my RAM troubleshooting.