A few years ago when the new batteries started appearing (Lipo etc) I was offered a new battery charger at the LHS that was told could charge everything. It was over $200 so not knowing any better I got one. After a couple of months it started playing up. It would come up with a single row of small squares right across the LCD screen. I searched for causes but came up blank. I dropped of RC for a couple years and when I came back found I could get similar chargers for $50 and less. I got one and have used it ever since.
Then today I was having a clean up and found the old charger in its box. I got it out and powered it up and sure enough the row of small squares still there and nothing working. I salvaged all the leads and things and was ready to put it in the rubbish. It has anti-opening screws that are a sort of hex type but a pin in the middle. On the way to the bin I passed the fridge and seeing as it is in the mid thirties I thought lets stick it in the freezer. I did this for five minutes and you've guessed it... it worked. So all this time it looks like it had a touchy temp setting and just needed cooling before using. Even though it was way overpriced it is a solid unit, full cast aluminum and even a cooling fan. (That is not very effective)
So next time any of your electronics starts misbehaving stick it in the freezer for a few minutes....