Good luck with it. Sounds like you're on your way to a better conclusion.
My solution for the dead PCE Duo that I'm currently dealing with:
Due to unforeseen circumstances the HU6280 chip is totally fried. I have a white PC Engine that has a cracked casing and broken power switch. I will be transplanting the chip from the white PCE over to the Duo using a heat gun or similar method.
I will keep modding stuff and I really think that I learnt many lessons through this horrible mess. Just wish it didn't take the "death" of a DUO-RX to give me the experience.
It can be frustrating, but all i can say is GO SLOW. Moving to quickly or with too much repetition (soldering, desoldering) is what causes most of the damage in these cases. Some of us, myself included, had to learn via Trial By Fire.
