AFAIK I selected correct version (A10, firmware 20U). But why doesn't the phone show any signs of life? Even if I plug in the charger, the phone doesn't show charging even though it was displaying charging normally before.You're correct with the version numbers.10x is A9,20U is A10 etc...
Is it possible that this is a hardware error (e.g. flash memory?)
But I have also a few question about your backup (backup_lg-v50s.rar):
First of all, are .bin files the same as .img files and could they be interchangeable?
Then please take a look to the following scenario:
I replace in your backup LUN5 partitions (fsc.bin, fsg.bin, modemst1.bin, modemst2.bin) by my saved copies. Then I restore this backup. This should unbrick the phone.
Am I right, and most importantly, is there any way to restore this backup without booting into normal mode?