RouterBOOT booter 6.49.1
RouterBoard 600A
CPU frequency: 533 MHz
Memory size: 128 MiB
NAND size: 64 MiB
Press <delete> key within 1 seconds to enter setup.
loading kernel... OK
setting up elf image... kernel out of range
kernel loading failed
Same thing still...
<edit>
I have found a fix for it:
Get the FWF bootloader for v7.1rc7 (tested that one only), paste into "files" in RB600 running 6.49.1, /sys routerboard upgrade
reboot and netinstall with 7.1rc7
Et voilá, the thing boots!
the catch is since the backup routerboot (2.20 in my case) cannot load a kernel from the new location, this may complicate a further unbricking attempt.
Reboot, yes? [y/N]:
y
system will reboot shortly
Rebooting...
[ 42.806006] reboot: Restarting system
RouterBOOT booter 7.1rc7
RouterBoard 600A
CPU frequency: 400 MHz
Memory size: 128 MiB
NAND size: 64 MiB
Press <delete> key within 1 seconds to enter setup.
loading kernel... OK
setting up elf image... OK
jumping to kernel code
Starting...
Starting services...
[admin@MikroTik] > system/resource/print
uptime: 5m19s
version: 7.1rc7 (testing)
build-time: Nov/25/2021 14:35:34
free-memory: 91.2MiB
total-memory: 128.0MiB
cpu: e300c1
cpu-count: 1
cpu-frequency: 399MHz
cpu-load: 1%
free-hdd-space: 39.4MiB
total-hdd-space: 64.0MiB
write-sect-since-reboot: 209
write-sect-total: 555109
bad-blocks: 0%
architecture-name: powerpc
board-name: RB600A
platform: MikroTik
[admin@MikroTik] >