Reddit mentions of Harry Potter: The Illustrated Collection (Books 1-3 Boxed Set)

I don't know of any version using simpler words. They do make these illustrated versions though. Maybe the pictures would help break up the text and keep his interest when he gets frustrated.

https://www.amazon.com/Harry-Potter-Illustrated-Collection-Books/dp/133831291X

https://www.amazon.com/Harry-Potter-Illustrated-Collection-Books/dp/133831291X/ref=mp_s_a_1_4?ie=UTF8&qid=1537218450&sr=8-4&pi=AC_SX236_SY340_FMwebp_QL65&keywords=harry+potter+illustrated+edition+book+1&dpPl=1&dpID=515cRsPd98L&ref=plSrch

Looks like they have the first 3 books done..here is a set for them but you can find them per book also.

Harry Potter: The Illustrated Collection (Books 1-3 Boxed Set) https://www.amazon.com/dp/133831291X/ref=cm_sw_r_cp_apa_i_0SCWDbFMSV8BW

They're gorgeous. Warning: there are spiders ALL OVER the 2nd one.

Harry Potter: The Illustrated Collection (Books 1-3 Boxed Set) https://www.amazon.com/dp/133831291X/ref=cm_sw_r_cp_apa_i_P123Cb505XW46

Probably too late for you at this point, but I recommend the illustrated editions that they have been coming out with. They've been coming out with one new book a year, and unfortunately they only have the first 3 books, and the 4th one is being delayed (because it's so big), but we really enjoyed them and I think they are a great for young kids. Here's a link:

https://smile.amazon.com/Harry-Potter-Illustrated-Collection-Books/dp/133831291X/

And Amazon has the first three in a bundle for cheap: Harry Potter: The Illustrated Collection (Books 1-3 Boxed Set) https://www.amazon.com/dp/133831291X/ref=cm_sw_r_cp_api_i_VUvBCbNJ9RJ86