Hello,
I am a real newbie, starting step by step using several tutorials for the installation of OpenWRT 21.02 on a Fritzbox 7362SL.... 
I made it to run the phyton script like this:
python eva_ramboot.py 192.168.178.1 openwrt-21.02.0-lantiq-xrx200-avm_fritz7362sl-initramfs-kernel.bin
> SETENV memsize 0x07aa5000
< 200 SETENV command successful
> SETENV kernel_args_tmp mtdram1=0x87aa5000,0x88000000
< 200 SETENV command successful
> MEDIA SDRAM
< 200 Media set to MEDIA_SDRAM
Is this how it sould look like?
Then finally the power LED is flashing red very fast.
According to what I read the box shoul after this be available under 192.168.1.1 but this is not the case.
Thus I can't copy the sysupgrade file using SCP to finish the installation...
I did it several times (power off, running pyhton script again...), same effect.
Can anybody help me out what's wrong? What may have caused the fast red flashing power LED
BR,
Peter