Got some time to watch your second video.
Qcode 'A0' displaying means 'IDE initialization is started' however when you are unable to enter the bios, it means that there is an issue with a drive and you only have M2 in their. The issue here is that you said it works in another computer correctly, so we are to assume from this the motherboard, BIOS or other hardware are the issue.
On other hardware question, I'm wondering about your GTX 1070,
Have you installed the patch
https://www.nvidia.com/en-us/drivers/nv-uefi-update-x64/ for 1.3 and 1.4 displays ?
And could you try replacing the cable between monitor and GPU with a 1.3 or 1.4 cable and see if the issue is still present.
In my mind that rule out other hardware ... leaving BIOS or motherboard.
I would then submit to ASUS Ticketed support the issue, ASUS might feel the need to help you outside of warranty period, but you never know if you don't ask. I have only good things to say about ASUS support from my past dealings with them and YMMV. Just dont get angry and jump through the hoops till you reach an end result, keep in mind, they like you to have with working products with their name on it, are not the enemy, and stuff happens.
Hope you find this helpful.
