Put it in and hit it with Prime95, if it works then you're fine, it's not going to short if it's not wet, though if you have "insurance" that covers negligence, no reason not to use it.
If the cleaning solution does not evaporate, then you should do as suggested in the other thread: use a pure organic solution to attempt to rinse it away. I don't know which would be best, but usually isopropanol and acetone are available at low cost. You can also use a fine bristled brush like an old toothbrush to help you clean around the pins if there is solid themal interface material still there (though it does not look like it in the photo). Allow to dry thoroughly before applying power.
Yeah I've just sorted an RMA, safest option, although yeah I feel like rinsing in the high purity organic solution would be a way to sort it.
I just felt with the time limit I had and no 2nd board to test on, should just send it back.
But no doubt they'll probably try to rinse and then test it.
After a day the CPU still stank of the citronella type stuff that's in the Articlean thermal remover and still has a 'damp' mark where it touched this side.
I mean it's pretty weird that it's kinda stained the pin side.
Anyway be interesting to see what they try if they're gonna attempt to fix it.
I just feel like there's no way of knowing if you 100% have all the stuff off, and it could be a little over-charge from that cationic stuff that would dmg board and cpu over long time maybe, anyway cheers.