Thank you very much Andreas and Nikolaus.
Using Nikolaus description of flashing the old uboot via sd card and
afterwards flashing with the latest uboot via sd card did work well.
For the record:
When I started the gta04 with the latest rootfs (no usb cable, holding
aux and putting battery in), I did not see a red flashing light. The
gta04 screen showed a menu with SD1, SD2, SD3, SD4, NAND, OFF etc.
I chose SD1 and after a short green screen, then a white screen, then
ca. 3 minutes loading, I was greeted by LXDE.
Using the hardware validation script via ssh I could see the kernel and
3 test_kernel ok 4.15.6-letux+ #2081 SMP PREEMPT Sun Feb 25 21:44:12 CET
2018 - recommended minimum: 4.10
36 test_uboot ok U-Boot 2016.11-00249-gc9d20fc fo Version string of
U-Boot in NAND
Looking forward to try out qtmoko2.
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