This won't be a how-to or what's wrong post but rather a story detailing a recent ordeal I handled.
On September 3 one of our church pastor's texted me late in the day and said the wifi wasn't working at the church. When I got there Wednesday morning I was told the underground sprinkler system had been damaged by lightning. For some reason they hadn't put the two together. After the local ISP replaced their perimeter hardware I went about troubleshooting the network within the building. I eventually replaced our router, three network switches, an IP phone, IP phone gateway, and the pastors PC. I was hoping everything was fixed (and from a network standpoint it was) but when I tested our sound and video equipment I found more problems. Our media PC would not turn on. I initially misdiagnosed the problem as a bad power supply but when that didn't fix it found that our camera interface box was fried and shorting out the USB port. When the device was unplugged the PC worked fine. So I replaced the interface with a new one but was then not able to get a video feed through the system. That was traced to a bad HDMI output port on the camera. I was also not able to get the PC to send video to our front and rear projectors. We were using a Kramer video switching box and it appears it's video import port is bad. We also had a MyMix in-ear system that was damaged.
When it's all said and done I suspect our repair bill will be close to $10,000. Insurance will cover the majority of it but it is still a headache. Fortunately we still have a building!