Uboot needed for pw2

Hello.
Let me explain my problem from the beginning

I broke my kindle Pw2 screen. So I went online and bought a new one, but of course, afterwards I was stuck with the invalid battery error.
So, I soldered the serial port, plugged in my ftdi, and went in Fastboot.
I am a Linux user, so I compiled Fastboot, and flashed system and diag. Unfortunately, as a newbie I tried to use a pw1 image. So I downloaded the right one, flashed it with Fastboot and tried to reboot in diags mode.

That's when I had problems. It said "mmcblk error". So I tried again to flash the system, and everything failed. Now it doesn't even have a serial, and bist doesn't work anymore.
I have the old Mac address (I think), the Kindle serial, but no board serial written.

I want to try to use Uboot, but I only find the one from eureka, which is for the kt if I understood correctly.

Does someone know about a correct Uboot, or a howto for this kind of full restore?

Last question, how should I do without the original serial numbers and Mac?

Thanks for reading :)