Well, by bypassing heat exchanger I was able to get coolant into system, so I could test that everything is ok before I buy new one. Engine radiator was leaking just under filler cap, so again something had to be done. It was still leaking between plastic ends in 10:1 ratio after quick patchwork, but was able to fill the radiator.
So my brother was checking under hood and my friend filmed short start up vid:
https://youtu.be/H9SVHl72nGs (my brothers YouTube channel)
To be continued…
PS received new radiator 1h ago. (not in pic)