Some Medions use F2, other you have to CTRL + ALT + SHIFT + INS.
Others have had success with ..
With F11 (instead of "Del") you get at boot time in the atrium one secret extended BIOS.
It appears to be a password window in which "am8888egh" is entered (without quotes).
Press Enter (The asterisks remain)
Now following key combination must be made quickly: Ctrl + Alt + Power button (Yes you read right ... the power button on the PC). Please press all 3 buttons at exactly the same, otherwise it will not work.
Tada .... You are in the extended BIOS: Overclocking, Advanced Chipset features, ... etc. Everything That which Medion not wanna know where your playing around on it is now open.
How accurate no idea, they are rebadged MSI laptops and people have also flashed standard firmware on them.