Well, as it would turn out, you guys were right. It was the controllers! What are the odds of two separate controllers going bad at the same time?!! I ordered a used controller off eBay and a battery replacement. I just flew the new...
You CAN replace the batteries in these. You can find them on eBay, a little cheaper on aliexpress, all of them being several weeks of shipping to come from China.
I don't know if it's causing your linking issue, which could happen if they start...