Device only with eMMC [loading ART]

Well, it could be that EMMC is fully corrupted and with that SBL1 too.
PBL is burned into the SoC ROM, so you can't really mess that up.
But it will not print anything on UART

Yes, of-course, the PBL is inside the IPQ40xx, knew that, didn't think of it.
Then I'll focus my attention now on getting access to the EMMC-chip.

Thanks for all your responses and guidance!

Hi, any chance that i could get in contact with you to obtain the full dump?
I'm looking at flashing the emmc (or a new one if this one is faulty). Yes, that means desoldering and resoldering.

If not, how did you obtain the full Dump?