I would much rather buy a pre-made rig. I tried building my own gaming PC once and was astonished at how much nuance there is to it. You also have to wade through long Youtube tutorials to understand how to do it all too, which I loathe doing. The phrase 'Money buys convenience' is doubly true when it comes to gaming rigs.
Sounds pretty painless to me! The "update bios" solution is in the 2nd and 3rd hits on google for his error code. A real headache are things like faulty components/drivers causing intermittent faults with no error code.
He did well to land on /r/buildapc - it's a real gem of the internet. Lovely people and super helpful.