Thank you for your help! I thought I was talking a different device because of the NS-B142 / NS-B142, but I know.
I think I found the right chip then: WINBOND 25Q128FV and I extracted this firmware. Can anyone confirm that this image is broken or smth? The BIOS is password locked if this is important....

Hello everyone,
I have a ThinkPad X1 Carbon 5th Generation with the motherboard DX120 NS-B142 and the BIOS Chip WINBOND 25Q80JVNIO.
Serial Number: PF-0RLY18
I tried to read the BIOS, but it seems to be corrupted.
The Laptop doesn't boot properly:
- after pressing reset button:
- 4x POST Beep
- rebooting
- 2x POST Beep
- no visual output to any screen (laptop screen or external monitor)
- fans spins but after a few seconds shuts down again
- keyboard and power button lights for split second

Any help would...