A620M-HDV/M.2+ & fw 3.18.AS01 => no boot

PC from signature from one day to another does not boot at all. Now I think it is possible it was testing the memory for some reason and that's why it seemed to hang on boot. However no tinkering with the bios or hw changes were applied. It worked fine last night and the next morning it did not boot. Given that the pc did not boot when it was first put together, and a bios update was necessary (it turned out that the factory bios was not compatible with the cpu), I decide to update the bios through the bios flashback feature to the latest (at the time of writing v3.18.AS01) version. The update was successful. However the bios does not boot to the nvme drive, every time the pc is powered on it goes straight to the bios screen. Also, there is no boot override nor boot priority devices to select although usb devices are recognized and can boot properly. Default Bios settings were used before the update and default settings are also set now. OS installed in nvme is archlinux. From pendrive, windows and linux can be booted properly.
How can I have my drives recognized for boot?
Thank you.