Hello Falcon_ASUS,
Thank you for your response and sorry for my late reply. Tried it and that destroyed windows to the extent that it was not recoverable after the "Disable Intel Volume Management Device (VMD) technology". Not a big thing as I took an image of the drive before starting the B1500 for the first time. The case was also escalated to level 2 support in spain and here their response:
"Una vez escalado su caso internamente, nos informan que si lo desea, podemos solicitar presupuesto a nuestro SAT para hacer el Upgrade el disco duro hdd o ssd del tipo sata3 ya que unicamente podemos garantizar el funcionamiento del equipo con el siguiente disco duro: 19200-41620700 SATA3 MN1000S 1TB 5400R 2.5' WD/WD10SPZX-80Z10T2/04.01A04 HDD".
In short, they wanted to sell me above mentionned disk as, according to them, this disk is the only one they can guarantee will work.
I eventually opened the laptop again and cleaned/reseated the disk-to-motherboard cable, and to my astonishment (and relief), the disk was recognized by the bios. After re-configuring the bios settings to the factory values and restoring the initial image to the M.2 SSD drive, all is fine now and the SATA drive works perfectly (dual Linux/Win11).
Thank you for reading me - chute
ps: this thread can be closed now