Wheelbuilding / Wheel Building / Wheel build help

Problem is Chrina ERD is 607 and Open PRO is 602, so the spokes are incompatible, unless it was built with too long spokes to start with. Check if the threads pop out of the nipple, only in that case you can re-rim.
A cheap replacement for Open PRO is Ambrosio Excursion, with similar enough ERD. Planet X used to have some (otherwise Evolution is the same thing but machined). It's a very good rim, last a lifetime and it's easier to fit a tyre on than it is on the Chrina

Open pro isn't 602 and Chrina isn't 607