That's like putting your miner on a ventilator, it will be a matter of time before they fail again, in fact, you could do the opposite and you would still have a good sucesss rate based on my own personal experience, put the bad hash boards in the freezer (in a sealed plastic bag of course) and many of them will run fine for a few days, I hope I will turn out to be wrong in your case, but those 17 series are TRASH.

What NotFuzzyWarm explained seems to make sense, I am not an electronic expert but I can tell you what causes 99% of the issues for those trash miners, it's the solder that keeps the chips attached to the PCB, greedy bitmain seems to have accepted the lowest bidder and made zero efforts in testing the quality of that medium-heat solder, some people also claim that the robots that did the job were also bad, but what we know for sure, the solder causes the problem in many different ways.

You will find solder balls shorting the chips, chips that lost some part of that solder underneath them so some legs are not in contact anymore, and all sorts of other things that bad solder/soldering leads to, so I am guessing that another reason in addition to what NFW mentioned is the fact the putting those hash boards in oven might have melted a solder ball that was shorting the chip and it fell off somewhere where it isn't causing an issue anymore, which is great news assuming that no other solder balls appear somewhere else.

But what you doing is great, try to fix those trash miners at the cheapest cost possible because they are not worth it.