RB1100AHx2 bootloop

Dear community,
I tried to upgrade the ros from the latest 6 to the latest 7.1.1.
The router is on boot loop all the time.
We tried to set it on netinstall but no success, the application couldn’t recognize it.
On the same pc, after many tries with the 1100 we did succesfully netinstall on RB750Gr3 which had exactly the same symptom.
We connected via serial and we get the following:

RouterBOOT booter 6.49.1

RouterBoard 1100AHx2

CPU frequency: 1066 MHz
Memory size: 2048 MiB
NAND size: 128 MiB

Press any key within 2 seconds to enter setup..
Ethernet link absent…
trying bootp protocol… failed
kernel loading failed

loading kernel… OK
setting up elf image… OK
jumping to kernel code
Could not mount [ 0.724663] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000
ubifs/yaffs file[ 0.733628] Rebooting in 5 seconds..

Any help to unbrick the router ?

Try to disable all the ethernet adapters in your computer except the one connected with the 1100 for the netinstall, disable the wireless adapters if any, disable any firewall program, use a simple switch between the computer and the 1100, try with other versions of netinstall …

I have already done that, in a laptop with windows 7
where I have accomplished after trying the 1100, successful netinstall on RB750Gr3 with the same symptom.

I found the solution, thanks to a guy asking in this forum.
Netinstall wasn’t working because RB1100AHx2 had to be in netboot mode (and not only NAND) while booting, and the only way to enable this was via terminal and serial null cable.
After that I was able to proceed with netinstall and revive the RB.

Ok, so you could not Netinstall because you had manually changed the default boot device from nand-if-fail-then-ethernet to nand-onlyhttps://wiki.mikrotik.com/wiki/Manual:RouterBOARD_settings#Settings
Also this parameter is not configured from terminal only

Actually I changed via serial the nand-only to etherboot, complete the netinstall , and then changed it again to nand-if-fail-then-ethernet.
I couldn’t change it from somewhere else except serial, because the router was rebooting continuously.

Weird situation with the ros 7. I have two other bricked RB750Gr3 with the same symptoms after the upgrade from ros 6.49.2.