@flohack Similar issue to before, after flashing and executing "adb reboot" the phone boots to the Google logo, sits there for 10-15 seconds, then enters a bootloop that eventually stops after 6-10 times in the bootloader with the message "ERROR: Slot Unbootable: Load Error".
dmesg -w did seem to see the device, here is a sample of the last few lines of output.
Device= 1.00
[ 1873.652354] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 1873.652358] usb 1-2: Product: Android
[ 1873.652361] usb 1-2: Manufacturer: Google
[ 1873.652363] usb 1-2: SerialNumber: HT7B91A02053
[ 1928.488153] usb 1-2: USB disconnect, device number 18
[ 1934.316312] usb 1-2: new high-speed USB device number 19 using xhci_hcd
[ 1934.466876] usb 1-2: New USB device found, idVendor=18d1, idProduct=d001, bcdDevice= 4.04
[ 1934.466882] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 1934.466885] usb 1-2: Product: AOSP on walleye
[ 1934.466888] usb 1-2: Manufacturer: Google
[ 1934.466890] usb 1-2: SerialNumber: HT7B91A02053
[ 1988.502910] loop: module loaded
[ 1988.556171] EXT4-fs (loop0): mounted filesystem with ordered data mode. Opts: (null)
[ 2202.191956] usb 1-2: USB disconnect, device number 19
[ 2596.561839] usb 1-2: new high-speed USB device number 20 using xhci_hcd
[ 2596.710679] usb 1-2: New USB device found, idVendor=18d1, idProduct=4ee0, bcdDevice= 1.00
[ 2596.710686] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 2596.710690] usb 1-2: Product: Android
[ 2596.710693] usb 1-2: Manufacturer: Google
[ 2596.710695] usb 1-2: SerialNumber: HT7B91A02053