olivir If your parents haven't updated in 6 months to 1 year...or less...I think my advice would be the worst in the world: find a way to update incrementally.
(first I don't know what's choking it to freeze....like 1000 updates worth of bandwidth? or a revised package during boot?)
I think you would start with your core elements, maybe 2 at a time...if we knew which packages were sequentially core...
or...figure out what the kernel after your current kernel is and manually install it? then baby steps? but that would have to be in the repo...or somewhere else?
I know nothing about the lts kernel...
obviously throwing darts NOT til one sticks but til maybe another corroborates it (bump!).
whenever I say to myself "I see nothing but a lot of pain trying to fix this" then BOOM someone comes along and says "oh thats easy, just do X and Y and reboot...." So we go that going for us...