Try user Quinn_at_HRR in the logitech remote forum. He does repairs and could probably tell you what's involved. I've opened my 520's a couple of times to work on buttons, but I don't remember what the screen interface looked like. I don't recall any ribbon cables or the screen falling out, so that probably means a contact for every row and column (meaning way to much work and little chance of a mere mortal getting right without special tools). You'd also have to find a donor 520 cheap enough to make it worthwhile.

If I were you, I'd tell the BF to buy you a new remote for Xmas, among other things. The 650 is a much nicer remote than the 520 anyway. Best Buy still has the 700 on sale for $50 I think.