2 batteries quit working on the same day. Coincidence?

I bought my Ego 20 inch mower, blower, and trimmer in the late spring of 2014. I had some issues with the mower after a year or so and they had to send me another one, but other than that everything has been great. I mowed the yard yesterday and put the 4.0amp battery on the charger and the charger doesn't kick on and the light blinks green one time then switches to intermittent red blinking. I try a different charger (I have the rapid and standard charger) with the same response. I wait until today to try again.....same response. I put the smaller, 2.0amp battery on the chargers yesterday and it works fine. I put it on there today after blowing off the lawn to get the leaves off of it.....same response. The chargers aren't kicking on and the battery juts stays red. It seems quite strange to me that 2 batteries and 2 chargers are doing the same things. I tried a different outlet....nothing. I called customer support, and lo and behold my warranty expired a couple of months ago and they can't help.

I'm not a conspiracy person, but are these things engineered to last right around the 3 year mark and then poop out after the warranty expires? It seems very odd to me. Is there something I'm doing wrong? Something I can do to fix it? I really don't want to spend $220 for a new battery. I could've bought a gas mower cheaper and paid for 10 years worth of gas for that price. Anyone else have this issue?