Help pls!! My system won't boot, not even live ISOs

Sorry if it doesn't belong here, but I'm quite desperate. If it's against the rules, please delete it.

My hurdles starting a couple of days ago when I decided to replace my Win10 install on my laptop for Cachy.

Everything started out fine, I managed to open the live image and start the installation. I wanted to do the full disk erase option which in hindsight wasn't a good idea. Around 2 mins in, it stopped with a partitioning error and I can't boot anything since then.

My old Win10 install is obviously gone, with the whole partition, but the worst thing is that I cannot even boot live images. I've tried Cachy, Arch, Mint, and even Gparted to try and sort out the partitions. Always the same issue: whenever I select the OS, it just switches to a slightly backlit black screen. I can do memtests though and it also let me access the EFI shell on Arch.

The only way I managed to boot some live ISOs was to switch to full legacy mode, but this way my nvme ssd is not recognized, so can't perform the install.

I've been suggested to perform a BIOS update in the Cachy Discord channel, but Lenovo only provides .exe installers for my model so without a windows installation on my machine I cannot even do that.

My specs:

Lenovo Legion 5 15ARH05H

AMD Ryzen 7 4800H

Nvidia GTX 1660Ti

factory nvme ssd 500gb

Someone please help!